DMP248 Dewpoint Transmitter OPERATING MANUAL U263EN-1.
PUBLISHED BY VAISALA Oyj P.O. Box 26 FIN-00421 Helsinki FINLAND Phone (int.): (+358 9) 894 91 Telefax: (+358 9) 894 9227 Telex: 122832 vsala fi Visit our internet pages at http://www.vaisala.com. © Vaisala 1999 No part of this manual may be reproduced in any form or by any means, electronic or mechanical (including photocopying), nor may its contents be communicated to a third part without prior written permission of the copyright holder.
_________________________________________________________________________CONTENTS Table of contents CHAPTER 1 GENERAL INFORMATION .......................................................................................................1 SAFETY ................................................................................................................................................................1 CHAPTER 2 PRODUCT DESCRIPTION .............................................................................
OPERATING MANUAL _______________________________________________________________ SERIAL COMMANDS ........................................................................................................................................... 46 Auto-calibration........................................................................................................................................... 46 Pressure compensation ..........................................................................................
_________________________________________________________________________CONTENTS GENERAL ............................................................................................................................... ............................75 ELECTRONICS ....................................................................................................................................................76 SERIAL INTERFACE MODULES ..........................................................................
CHAPTER 1_______________________________________________________ GENERAL INFORMATION CHAPTER 1 GENERAL INFORMATION Safety Throughout the manual important instructions regarding the safety considerations are focused as follows. WARNING Warning denotes a hazard. It calls attention to a procedure, practice, condition or the like, which, if not correctly performed or adhered to, could result in injury to or death of personnel. CAUTION Caution denotes a hazard.
CHAPTER 2_______________________________________________________ PRODUCT DESCRIPTION CHAPTER 2 PRODUCT DESCRIPTION General characteristics The DMP248 transmitter is a microprocessor-based instrument for the measurement of dewpoint temperature in low humidities. The transmitter measures other quantities as well: relative humidity, temperature and ppm concentration (dry). When the dewpoint temperature is below 0 °C, the transmitter calculates the frostpoint instead of the dewpoint.
OPERATING MANUAL _______________________________________________________________ The operating principle of the DMP248 The DMP248 transmitter incorporates the DRYCAP® sensor which is optimized to be used in low humidities but has also an excellent tolerance against condensation. The DRYCAP® sensor uses an operating principle based on changes in capacitance as its thin polymer film absorbs water molecules together with a combined temperature measurement with a Pt 100 resistive temperature sensor.
CHAPTER 2_______________________________________________________ PRODUCT DESCRIPTION The function Pws(T) is well known from literature. Thus, it is possible to determine the offset (RH 0) if measurements are made at two or (preferably) more temperatures assuming a constant Pw during the process. 0.4 0.3 20°C RHout(%) 0.2 0.1 30°C 0 -0.1 -0.2 -0.3 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 1/Pws(T) FIGURE 2-1 Device output during hypothetical offset calibration cycle.
OPERATING MANUAL _______________________________________________________________ FIGURE 2-2 The DRYCAP sensor mounted on a DMP248 probe. Note that the auto-calibration takes place only if the DMP248 is used in ambient humidities below 10 %RH (dewpoint below -12 °C at 20 ° C) and at ambient temperature 0...+80 °C. Use in high pressure If the process pressure differs from the normal ambient pressure, the value has to be entered in the transmitter memory to ensure the best possible measurement accuracy.
CHAPTER 3_______________________________________________________________ INSTALLATION CHAPTER 3 INSTALLATION Selecting the place of installation Select a place which gives a true picture of the environment or process; also select a place that is as clean as possible. Air should circulate freely around the sensor. It is recommended that the sensor head is installed directly in the process through the ball valve assembly.
OPERATING MANUAL _______________________________________________________________ 104 120 CL ENT ø6.5 65 133 145 Dimensions of the DMP248 electronics housing (in mm). FIGURE 3-1 NOTE 1. Always mount the transmitter housing with the cable bushings pointing downwards to ensure IP65 (NEMA4) rating 2. Make sure that the connection cable has the right thickness (∅7...10 mm) and that the cable bushing is carefully tightened. 3.
CHAPTER 3_______________________________________________________________ INSTALLATION NOTE Take care not to damage the pipe of the probe. If the pipe is damaged, the probe head is less tight and it will not go through the clasp nut. Mounting; overview fitting body hex = 24mm tapered thread R1/2 ISO 7/1 parallel thread G1/2 ISO 228/1 (BS 2779, JIS B0202) ø19mm drilling >10.5mm >40mm sealing with: 1. LOCTITE® No 542 + activ. No 7649 (t=-55...+150 °C) 2. MEGA-PIPE EXTRA No 7188 (t=-55...+170 °C) 3.
OPERATING MANUAL _______________________________________________________________ NOTE Be careful not to tighten the clasp nut more than 60° as this may result in difficulties when trying to open it. The probe is delivered with non-leaking screw A mounted. For bypass measurements, this screw is removed and replaced with leaking screw B (included) and an O-ring is placed on the groove of the sintered filter prior to installation. Make sure to tighten the screw carefully. Screw B has a small (0.
CHAPTER 3_______________________________________________________________ INSTALLATION If the sensor head is installed in a pressurized chamber, always make sure that the pressure of the chamber is equalized with the ambient pressure prior to removing the probe. capped nut DIN 917-M22x1.
OPERATING MANUAL _______________________________________________________________ probe non-leaking screw A handle >30 mm ball of the ball valve (hole diameter at least 14 mm) process pipe / chamber FIGURE 3-7 NOTE Installing the sensor head through the DMP248BVS ball valve assembly. The probe can be installed in the process through the ball valve assembly provided that the process pressure is less than 10 bars.
CHAPTER 3_______________________________________________________________ INSTALLATION • STEP 1: mount the probe with the ball valve assembly closed; tighten the clasp nut manually. bushing R1/2 cone/G1/2(40 bar) e.g. Camozzi 2520-1/2-1/2 (the bushing serves for moving the probe (sinter) to such a distance from the ball valve that the valve can be closed) ball valve 1/2" (40 bar) e.g.
OPERATING MANUAL _______________________________________________________________ STEP 2: open the ball valve assembly. 148 mm manual press tool adjustment range 120mm • probe pipe ø5.5 marking groove clasp nut (hex 27 mm) 61 handle fitting ferrule fitting body (hex. 24 mm) leak screw (B) (hex. 1.5 mm) ø14 15 29 (40) ball of the ball valve O-ring > = ø13.5 DRYCAP® sensor filter 14 R1/2 ISO 7/1 FIGURE 3-9 Installing the probe through the ball valve assembly; step 2 (measures in mm).
CHAPTER 3_______________________________________________________________ INSTALLATION STEP 3: push the probe head through the ball valve assembly into the process. If the pressure is high, use a manual press tool. Note that the sensor head must be pushed so deep that the filter is completely inside the process flow. MANUAL PRESS TOOL VALVE OPEN VALVE CLOSED FILTER FIGURE 3-10 Installing the probe through the ball valve assembly; step 3.
OPERATING MANUAL _______________________________________________________________ gas escape channel: use this position for by-pass measurements leak screw (B) NOTE keep the marking groove in sight when using leak screw (B) O-ring sintered filter DRYCAP® sensor process pipe or chamber FIGURE 3-11 Installing the sensor head for by-pass measurements. When pushing the probe head through the ball valve assembly, be careful not to break the sintered filter.
CHAPTER 3_______________________________________________________________ INSTALLATION Mounting the probe with a quick connect The probe can also be installed with a quick-connect, which acts as a closing valve between the process and the probe. The installation can be easily done even in small ducts with standard parts, and the probe is easily removed when necessary. It is necessary for the probe to be installed in the leak-through position for a reasonable response time.
OPERATING MANUAL _______________________________________________________________ Sample cell It may be necessary to use the sample cell if the process (e.g. a pipe) is too small for the DMP248 sensor head. Furthermore, if the process is very hot (>80 °C) or particularly dirty, the probe is installed in a sample cell behind a cooling coil and/or filter. In this case, the ambient temperature must be at least 10 °C warmer than the process dewpoint in order to avoid condensation in the sample tubing.
CHAPTER 3_______________________________________________________________ INSTALLATION process pipe 28 6 6 metal plate thickness e.g. 3mm (1/8") AISI 316 SAMPLE CELL DMP248SC S PUSH PROBE SINTER AGAINST THIS EDGE, TIGHTEN THE CLASP NUT.
OPERATING MANUAL _______________________________________________________________ Optional installation by means of the sampling system DSS10 When the operating environment is not suitable for direct installation of the measurement probe, an alternate solution could possibly be found with the complete sampling system DSS10. The sample system allows for greater measurement accuracy and stability by controlling the temperature, pressure and filtration levels to optimize the performance of the sensor.
CHAPTER 3_______________________________________________________________ INSTALLATION Grounding A single electrical cable with a screen and three to ten wires is recommended for power and analogue output/serial bus connections. The cable diameter should be 7...10 mm. The screen of the electrical cable must be grounded properly to achieve best possible EMC performance. Recommended cable shield is done in the cable gland as shown.
OPERATING MANUAL _______________________________________________________________ • tighten the nut • connect the wires into the screw terminals and fasten a cable tie around the wires cable tie transmitter housing gland brass disks rubber ring nut NOTE When the cable is grounded as explained, the metallic parts of the sensor head, the screen of its cable, the transmitter housing and the screen of the signal cable to external system are all connected to each other.
CHAPTER 3_______________________________________________________________ INSTALLATION CH1+ CH1 CH2 + CH2 - Connections CH1- and CH2- are connected together internally + V mA CURRENT/VOLTAGE OUTPUTS + V mA 24 V + POWER SUPPLY (INTERNAL OR EXTERNAL) Do not use power supply ground (-) as output signal ground X2 X1 OPENED COVER OF THE DMP248 FIGURE 3-18 Power supply Output signals Electrical connections 24 VDC 24 VAC (see Chapter Connection to an AC supply) 0...20 mA 4...20 mA 0...1 V 0...5 V 0...
OPERATING MANUAL _______________________________________________________________ Connection to an AC supply The DMP248 transmitter can also be connected to an AC supply without an external rectifier. However, when more than one transmitter is connected for example to one 24 VAC transformer, a common loop is formed and there is an increased risk of a shortcircuit. To avoid this, always use separate floating supply for each transmitter (see FIGURE 3-19A).
CHAPTER 4_____________________________________________________________ COMMISSIONING CHAPTER 4 COMMISSIONING When the DMP248 transmitter leaves the factory, its measurement ranges and output signals have already been selected. The user can subsequently change the measurement units between metric and nonmetric and select and scale the output signals with software functions, see Chapter Selecting and scaling the analogue output quantities and Appendix 1.
OPERATING MANUAL _______________________________________________________________ Selecting the analogue outputs CH1 CH2 The DMP248 transmitter can be ordered ready with the current or voltage outputs required. If the outputs need to be changed, move the jumpers in connector X15 into positions as shown in FIGURE 4-2. CH1 CH2 CH1 CH2 CURRENT OUTPUTS 0 ... 20 / 4 ... 20 mA CH1 CH2 CH1 CH2 VOLTAGE OUTPUTS 0 ... 5 V / 0 ... 10 V CH1 CH2 CH1 CH2 VOLTAGE OUTPUTS 0 ... 1 V CH1 CH2 CH1 0 ...
CHAPTER 4_____________________________________________________________ COMMISSIONING command ASCL and the display command 0RGH Õ $QDORJ RXWSXWV Õ 6FDOH . All jumpers are used only with the 0...1 V outputs. When other outputs are in use, the spare jumpers are kept in connector X55.
OPERATING MANUAL _______________________________________________________________ Connecting the RS 232C serial bus RX GND TX NC X6 OPENED COVER OF THE DMP248 FIGURE 4-4 Serial bus connections. To connect a PC to the DMP248 transmitters via the RS 232C serial bus, one of the following cables is required. The type of cable depends on the terminal and the connector type.
CHAPTER 4_____________________________________________________________ COMMISSIONING When the serial bus has been connected between the PC and the transmitter, the PC is switched on. When using a PC, a terminal emulation programme (e.g. Procomm Plus, Datastorm or Windows terminal) is started.
OPERATING MANUAL _______________________________________________________________ RX GND TX X17 FIGURE 4-6 NOTE Location and connections of connector X17. Some PC computers can generate interferences to the measured humidity and temperature values if the transmitter and the PC are connected to different mains outlets. To minimize the possibility of these interferences, always use the same main outlet (same phase of the main electricity) for the PC and the power supply of DMP248.
CHAPTER 4_____________________________________________________________ COMMISSIONING transmitter is reset; if the jumper is in place when power is turned on, the transmitter does not work. After jumper insertion the transmitter is in STOP mode, ready to receive commands. The same method is used when the transmitter is in POLL mode and the user has forgotten its address. CAUTION Inserting a jumper in any other place in connector X16 voids the guarantee of the transmitter.
CHAPTER 5________________________________________________________________ COMMANDS CHAPTER 5 COMMANDS The DMP248 transmitter uses a microprocessor; therefore, its configuration can be set according to the user’s needs. This is done through commands, either utilizing the menus on the local display or giving commands through the serial interface (see Appendix 1). Most often, the commands are used to change the settings of the two analogue channels.
OPERATING MANUAL _______________________________________________________________ • serial commands: CRH, CT, FCRH, ACAL; AMODE, ASEL, ASCL In the following, the description of these functions is preceded with a reminder of the security lock jumper: Disconnect the security lock jumper! LED commands NOTE If the transmitter has a display/keypad cover, the LED commands cannot be used.
CHAPTER 5________________________________________________________________ COMMANDS Display/keypad commands Display mode In the display mode, the transmitters output measurements on the display; different quantities can be scrolled with the arrow keys. The first line is scrolled with button σ and the second line with button τ; all selections are stored with ENTER. The selected quantities appear on the display also after power failure. After the reset, the transmitters are always in the display mode.
OPERATING MANUAL _______________________________________________________________ With some commands (e.g. calibration) the figures are changed using the arrow keys. When an arrow key is pressed continuously for a while, the numbers start changing at an increasing rate. Auto-calibration • Select 0RUH in the main menu and then again 0RUH in the second More menu. Select 'U\ FDO and then 6HWWLQJV. • The interval parameter defines the frequency of auto-calibration cycles.
CHAPTER 5________________________________________________________________ COMMANDS • This parameter defines the measuring time of the change in dewpoint prior to the auto-calibration (see the parameter 0D[ G7GS . • If the setting is correct, press ENT. • If the setting needs to be changed, press CL and change the value with arrow keys. Acknowledge the setting with ENT. • This parameter defines the maximum correction (%RH) the transmitter does during each auto-calibration cycle.
OPERATING MANUAL _______________________________________________________________ Forced auto-calibration • Select 0RUH in the main menu and then again 0RUH in the second More menu. Select 'U\ FDO and then &DOLEUDWLRQ • Select 0RUH in the main menu and then again 0RUH in the second More menu. Select 'U\ FDO and then &DOLEUDWLRQ. The following is displayed: &DOLEUDWLRQ SUHVV DQ\ NH\ WR DERUW • If you press any key, the calibration is interrupted.
CHAPTER 5________________________________________________________________ COMMANDS − the quantity (mA/V) starts flashing; it can be changed with the arrow keys and acknowledged with the ENT key − the lower limit starts flashing − acknowledge the lower limit with ENT or start changing it by pressing CL; a new lower limit is given one character at a time with the arrow keys − the upper limit starts flashing − acknowledge the upper limit with ENT or start changing it by pressing CL; a new upper limit is given
OPERATING MANUAL _______________________________________________________________ • If the settings need to be changed, press CL: − the quantity starts flashing; it can be changed with the arrow keys and acknowledged with the ENT key − the lower limit starts flashing − acknowledge the lower limit with ENT or start changing it by pressing CL; a new lower limit is given with the arrow keys − the upper limit starts flashing − acknowledge the upper limit with ENT or start changing it by pressing CL; a new uppe
CHAPTER 5________________________________________________________________ COMMANDS • Select the parameter to be changed with the arrow keys and ENT key.
OPERATING MANUAL _______________________________________________________________ Setting the transmitter address Address is used when more than one transmitter is connected to one serial bus; it makes it possible to communicate with one transmitter at a time. • Select 0RUH in the main menu and $GGU in the More menu; the following is displayed: • Pressing ENT returns the programme to the main menu. • Pressing CL deletes the old address; enter the new address with the arrow keys.
CHAPTER 5________________________________________________________________ COMMANDS that can be given through the serial interface is S (stop) which ends the RUN state. In the STOP state serial commands are given to the transmitters. Measurements are then output only by entering command SEND. The POLL state is used when more than one transmitter is connected to the same serial bus; a single transmitter can be addressed and communicated with.
OPERATING MANUAL _______________________________________________________________ • press CL • the number starts flashing • if the interval needs to be changed, press CL again and enter the new interval; otherwise press ENT • the unit (s, min, h) starts flashing • the unit can be changed with the arrow keys and acknowledged with ENT • after this the programme returns to Mode menu Others Pressure compensation The pressure is used for pressure compensation of the DRYCAP sensor in order to ensure
CHAPTER 5________________________________________________________________ COMMANDS Setting the date • Select 0RUH in the main menu; select 'DWH in the More menu: • If the date is correct, acknowledge it by pressing ENT; this takes the programme back to the More menu. • If the date needs to be changed, press CL.
OPERATING MANUAL _______________________________________________________________ − the seconds (32) start flashing; use the arrow keys to change them and press ENT NOTE The transmitter does not have a real-time clock with backup battery. This means that the date and time settings are not permanent. Serial commands More detailed descriptions of the serial commands can be found in Appendix 1. Here only the most commonly used command sequences are described.
CHAPTER 5________________________________________________________________ COMMANDS The 0D[ G7GS parameter defines the maximum allowed change of the dewpoint value during the pre-defined G7GS time. If the change in dewpoint value exceeds the limit, the calibration is not started. The auto-calibration is done only after process is stabilized. The transmitter retries untill the calibration is succesfully complited. Note that normally, this parameter does not have to be changed.
OPERATING MANUAL _______________________________________________________________ Pressure compensation PRES pppp.pp where pppp.pp = absolute pressure (hPa). value has to be entered in the transmitter memory in order to ensure the best possible measurement accuracy. The pressure setting is used for pressure compensation of the DMP248 transmitter. The pressure is given in hPa/mbar; for converting pressure units, see Appendix 8.
CHAPTER 5________________________________________________________________ COMMANDS Analogue outputs Setting the analogue outputs Disconnect the security lock jumper! AMODE a bb.bbb cc.ccc d ee.eee ff.fff a = channel 1: U I bb.bbb = lower limit of channel 1 cc.ccc = upper limit of channel 1 d = channel 2: = voltage output = current output U = voltage output I = current output ee.eee = lower limit of channel 2 ff.fff = upper limit of channel 2 The bb.bbb, cc.ccc, ee.eee and ff.
OPERATING MANUAL _______________________________________________________________ xxx = channel 1’s quantity yyy = channel 2’s quantity (RH, T, Td, ppm) Example: dewpoint temperature selected on channel 1 and temperature on channel 2 >ASEL Ch1 ( Ch1 ( Ch2 ( Ch2 ( > Td Td Td T T T ) lo ) hi ) lo ) hi -50.00 10.00 10.00 100.
CHAPTER 5________________________________________________________________ COMMANDS Stopping the measurement output S Ends the RUN mode; after this command all other commands can be used. Outputting the reading once SEND in STOP mode or SEND aa in POLL state aa = address of the transmitter when more than one transmitter is connected to a serial bus (0...99) Output: Td= -9.3 ’C PPM= Td= -9.3 ’C PPM= 2733 T= 22.1 ’C RH= 10.4 %RH 2730 T= 22.1 ’C RH= 10.4 %RH ...
OPERATING MANUAL _______________________________________________________________ Serial bus settings SERI b p d s x b p d s x = = = = = bauds (300, 600, 1200, 2400, 4800, 9600) parity (n = none, e = even, o = odd) data bits (7 or 8) stop bits (1 or 2) duplex (H = half, F = full) The settings can be changed one parameter at a time or all parameters at once: >SERI O 4800 O 7 1 HDX changing parity only >SERI 600 N 8 1 F 600 N 8 1 FDX changing all parameters The processor does not allow t
CHAPTER 5________________________________________________________________ COMMANDS Resetting the transmitter RESET Operating the transmitter via the serial bus Setting the serial interface SMODE xxxx xxxx = STOP, RUN or POLL In STOP mode: measurements output only by command, all commands can be used In RUN mode: outputting automatically, only command S can be used In POLL mode: measurements output only with command SEND.
OPERATING MANUAL _______________________________________________________________ Example: relative humidity calibration is performed at transmitter 2 which is in POLL state >OPEN 2 >CRH ... >CLOSE opens the line to transmitter 2 calibration started line closed 54 _____________________________________________________________________ U263EN-1.
CHAPTER 6_______________________________________________________________ CALIBRATION CHAPTER 6 CALIBRATION The DMP248 transmitter has been fully calibrated at the factory so there should be no immediate need for recalibration. The transmitter should be calibrated only if there is reason to believe that the adjustments have changed. The adjustments of the temperature measurement channel and the analogue outputs are particularly stable and in normal circumstances, there is no need to recalibrate them.
OPERATING MANUAL _______________________________________________________________ NOTE As relative humidity is a temperature dependent parameter, the probe and the salt bath calibrator have to stabilize to the same temperature for best accuracy. Two-point calibration procedure A two-point humidity calibration should be performed in stable conditions using saturated salt solutions as references.
CHAPTER 6_______________________________________________________________ CALIBRATION • Press any key and enter the second point value and press . RH • : xx.x Ref2 ? yy.y The stabilization of the sensor can be monitored here as well by entering c instead of the reference value. Using display/keypad commands • Leave the calibrator and the transmitter for at least 4 hours in the same space so that their temperatures have time to equalize. Remove the filter cap on the transmitter.
OPERATING MANUAL _______________________________________________________________ • Place the sensor head in the calibration hole of the LiCl bottle (dry end reference) in the humidity calibrator. • Connect an ammeter/voltmeter to the analogue outputs (connector X2). Give command l. At the first calibration point the LED on the left flashes; adjust the first point (offset) with the arrow switches to the value given in the calibration table (Chapter 0) and press ENT switch.
CHAPTER 6_______________________________________________________________ CALIBRATION Humidity calibration table TABLE 6-1 Temperature LiCl 4...20 mA 0...20 mA 0...1 V 0...5 V 0...10 V NaCl 4...20 mA 0...20 mA 0...1 V 0...5 V 0...10 V Greenspan’s calibration table °C °F %RH 15 59 * 20 68 11.3 5.81 2.26 0.113 0.565 1.13 25 77 11.3 5.81 2.26 0.113 0.565 1.13 30 86 11.3 5.81 2.26 0.113 0.565 1.13 35 95 11.3 5.81 2.26 0.113 0.565 1.13 %RH 75.6 16.10 15.12 0.756 3.780 7.56 75.5 16.08 15.10 0.755 3.
OPERATING MANUAL _______________________________________________________________ • Check the transmitter against the reference. • Give command CT , enter the first point value and press : >CT T : xx.x Ref1 ? yy.y Press any key when ready • If you want to see how the sensor stabilizes to the reference temperature, enter c instead of the first reference: T : 0.90 Ref1 ? c T : 0.55 Ref1 ? c T : 0.55 Ref1 ? 0.0 Press any key when ready...
CHAPTER 6_______________________________________________________________ CALIBRATION • Connect an ammeter/voltmeter to the analogue outputs (connector X2). Give command l. At the first calibration point the LED on the left flashes; adjust the first point (offset) with the arrow switches to the same reading with the reference and press ENT switch. • After adjusting the offset point and pressing ENT the second LED from left flashes. Press ENT without changing the output value.
OPERATING MANUAL _______________________________________________________________ • The stabilization of the sensor can be monitored well by entering c instead of the reference value. Using display/keypad commands • Leave the reference instrument and the transmitter for at least 4 hours in the same space so that their temperatures have time to equalize. Remove the filter cap prior to calibration.
CHAPTER 6_______________________________________________________________ CALIBRATION • Check that the reading corresponds with the reading of the reference instrument. If not, adjust the second point. • If necessary, adjust with the arrow switches to the correct value and press ENT. At the second calibration point the second LED from the left flashes.
OPERATING MANUAL _______________________________________________________________ • Enter the measured lower end current/voltage on channel 1. • Enter the measured upper end current/voltage on channel 1. • Connect the meter to the output of channel 2 and enter the measured lower end current/voltage on channel 2. • Enter the measured upper end current/voltage on channel 2.
CHAPTER 6_______________________________________________________________ CALIBRATION • the LED on the left flashes; set the low end of channel 2 with the arrow keys and press ENT • the second LED from the left flashes; set the high end of channel 2 with the arrow keys and press ENT The analogue outputs are calibrated to ensure that outputs are correctly scaled: for example, when the output is scaled to 4...20 mA, the low end of the scale is 4 mA and high end 20 mA exactly. However, when 0...
CHAPTER 7____________________________________________________________ MAINTENANCE CHAPTER 7 MAINTENANCE Reference measurements Reference measurements are needed to verify whether the transmitter readings are within specifications. This way the user can check if the transmitter needs calibration or service. The reference measurement should be made as close to the checked sensor as possible and the readings should be read at the same time, when possible.
OPERATING MANUAL _______________________________________________________________ ERRS If there are no error messages, only a prompt is displayed: >ERRS > When errors have occurred, the transmitter outputs the error code (see Appendix 5 for all error messages): >ERRS E40 f ( all ) > out of range Temperature channel adjustment with Pt 100 simulators Switch the power off and disconnect the wires to the Pt 100 sensor from solder lugs TP5, TP6 and TP7.
CHAPTER 7____________________________________________________________ MAINTENANCE Adjustment using serial commands Give command CT and enter the first point value and press : >CT ’C : xx.x Ref1 ? yy.y Press any key when ready Set the Pt 100 simulator at the highest temperature to be calibrated, and press any key. Enter the second point (gain) reference reading. If second reference is not needed, press to complete one point offset correction.
OPERATING MANUAL _______________________________________________________________ corresponding temperature value from a Pt 100 conversion table or calculate it using the following equation: T = D0 + R x {D1 + R x [D2 + R x (D3 + R x D4)]} (7-1) where D0 D1 D2 D3 D4 = = = = = -243.5673014 2.278542701 0.002050681 -6.15025E-06 1.34949E-08 Measurement of output currents using test points X15 CH1 + + CH2- CH2+ CH1- CH1+ If a current output has been connected e.g.
CHAPTER 7____________________________________________________________ MAINTENANCE mA X2 CH1+ CH1CH1+ TEST POINTS FIGURE 7-4 CH1- RL Circuit diagram of the analogue output current test points Adjusting the contrast of the display The contrast of the display can be adjusted using the trimmer "LCD display contrast" located next to the press switches.
CHAPTER 8____________________________________________________________ TECHNICAL DATA CHAPTER 8 TECHNICAL DATA Measured variables Dewpoint temperature Measurement range -60...+80 °C (below 0 °C DMP248 outputs frostpoint) Dewpoint accuracy (see figure below) FIGURE 8-1 ± 2 °C (-50...+80 °C) Measurement range and accuracy. Response time (90%) at flow rate 0.
OPERATING MANUAL _______________________________________________________________ Temperature Measurement range for specified Td accuracy -40...+80 °C 0...+80 °C Typical accuracy of electronics at +20 °C (+68 °F) ±0.1 °C Typical temperature dependence of electronics 0.005 °C/°C Temperature sensor Pt 100 IEC 751 1/3 Class B Relative humidity Measurement range Accuracy at 20 °C RH< 10 %RH RH> 10 %RH 0...100 %RH ± 0.025 %RH + 8.75% of reading ± 0.
CHAPTER 8____________________________________________________________ TECHNICAL DATA General Sensor DRYCAP S sensor Connections screw terminals, 0.5 mm2 wires (AWG 20), stranded wires recommended Operating voltage 24 VDC/ isolated VAC (20...28 V) 115 VAC/230 VAC with power supply module Power consumption 100 mA maximum (24 VDC) Recommended external load for current outputs <500 Ω 0...1 V voltage output >2 kΩ (to ground) 0...5 and 0...
OPERATING MANUAL _______________________________________________________________ Sensor head dimensions: PROBE PUSHED DOWN PROBE UP ø5.5 cable length 2, 5 or 10 m adjustment range120 mm R1/2 ISO 7/1 178 29 31 R1/2 ISO 7/1 ø13.5 Weight of display cover 420 g User interface 3 keys and 4 LEDs inside the housing or local display keypad (option) Display (option) 2 x 16 character alphanumeric LCD 3.85 mm (0.
CHAPTER 8____________________________________________________________ TECHNICAL DATA Electromagnetic compatibility The emission and immunity tests have been performed according to standards EN50081-1 and EN50082-2.
OPERATING MANUAL _______________________________________________________________ CHAPTER 9 OPTIONS Power supply 24 VDC (VAC)(standard), 115/230 VAC Serial interface RS 232C (standard), RS 485/422, current loop Cable length 2, 5 or 10 metres Alarm output 2 relays 8 A/ 230 V SPCO (Single Pole Change Over) for adjustable low and high alarm Display cover cover with or without local display & keypad 78 _____________________________________________________________________ U263EN-1.
CHAPTER 10_______________________________________________ SPARE PARTS AND ACCESSORIES CHAPTER 10 SPARE PARTS AND ACCESSORIES Order code 16452 DRYCAP S HMP230PW 5237 HMP230RS HMP230CL DMP240ALSP 17143 HMP248SC DSS10 DMP248BVS 16611 Description Sintered filter, stainless steel DRYCAP® S dewpoint sensor Power supply module Fuse 160 mA T 5x20 mm for power supply module RS 485/422 serial module Current loop module Alarm output unit Fuse 8 A for alarm output unit Sample cell Sample system Ball valve set Calib
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ APPENDIX 1 SERIAL COMMANDS APPENDIX 1 AUTO-CALIBRATION COMMANDS DRYCAL Defining the frequency of auto-calibration cycles DCAL Forced auto-calibration ANALOGUE OUTPUT COMMANDS AMODE Setting the analogue outputs ASEL Selecting the scaling the analogue output quantities ASCL Scaling the analogue outputs CALIBRATION COMMANDS CRH Relative humidity calibration CT Temperature calibration ACAL Calibrating the analogue outputs L O
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ Auto-calibration commands DRYCAL Defining the frequency of auto-calibration cycles DRYCAL >drycal DCAL ON Interval min : 360 ? Max dTdp: 2.00 ? dTdp time s : 10 Max corr. : 0.040 ? The interval parameter defines the frequency of auto-calibration cycles. When the transmitter is turned on, the first auto-calibration takes place after on hour unless the frequency has been set to less than an hour.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ DCAL Forced auto-calibration DCAL >dcal Calibration... any key to abort > (appears when the auto-calibration is completed, max. 60 - 70 seconds) If you press any key, the calibration is interrupted. If no key is pressed, the calibration takes place immediately. The text above is displayed during the calibration.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ >AMODE U 0 1 U 2 10 Ch1 : 0.000 ... 1.000 V Ch2 : 2.000 ... 10.000 V The current settings can be checked by giving the command without any parameters: >AMODE Ch1 : 0.000 ... 20.000 mA Ch2 : 0.000 ... 20.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ The outputs and their scales can also be given directly with the ASEL command. ASEL xxx yyy aaa.a bbb.b ccc.c ddd.d xxx yyy aaa.a bbb.b ccc.c ddd.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ Calibration commands CRH Relative humidity calibration Disconnect the security lock jumper! CRH With this command the transmitters can be calibrated against two RH references. Two-point calibration is performed using saturated salt solutions in controlled conditions according to the following instructions: >CRH RH : 12.00 Ref1 ? 11.3 Press any key when ready ... RH : 76.00 Ref2 ? 75.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ In one-point offset correction, the Ref2 prompt is acknowledged with : >CT T : 0.80 Ref1 ? 0.0 Press any key when ready ... T : 75.50 Ref2 ? If the stabilization of the sensor to the temperature of the calibrator or the reference needs to be monitored, the measurement output can be repeated by giving command c at Ref1 and Ref2: >CT T : 0.80 T : 0.40 Press any key T : 56.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ LI Entering linear correction coefficients Disconnect the security lock jumper! LI The LI command is one way of calibrating the transmitters. >LI RH RH Ts Ts offset gain offset gain : : : : 0.000 1.000 0.000 1.000 ? -.6 ? ? ? .4 The factory settings are offset 0 and gain 1.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ S Stopping the measurement output S Ends the RUN state; after this command all other commands can be used. SEND Outputting a reading once SEND in STOP state or SEND aa in POLL state aa = address of the transmitter when more than one transmitter is connected to a serial bus (0...99; set with command ADDR) Outputs the current measurement readings via the serial line.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ ERRS Outputting error messages ERRS During operation error messages are not output automatically through the serial interface. If there is any reason to doubt that there is something wrong with the transmitter, possible error messages can be output with command ERRS.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ When this is changed into 10 minutes, the command is: >INTV 10 Output intrv. : 10 min The unit is changed into seconds with: >INTV S Output intrv. : 10 s The change can also be done with one command: >INTV 10 S Output intrv. : FORM 10 s Setting the output format FORM "xxx...xxx" ? zzz...zzz xxx...xxx zzz...
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ Any text can be written in the command and it appears in the output. For example: RH: \UUU.U\ T: \+TT.TT\\r RH: 54.0 T: +25 The format can be deleted by giving \ as a parameter: Note. only one space before \ and none after >FORM \ or >FORM "xxx...xxx" ?\ An example of a format suitable for use in Microsoft Excel spreadsheets: >FORM "xxx...xxx" ?\UUU.U\\t\TTT.T\\t\DDD.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ Inactivating the time output >ftime off Form. time >r RH= 19.4 %RH RH= 19.8 %RH RH= 20.6 %RH RH= 20.5 %RH RH= 19.9 %RH RH= 19.6 %RH ... FDATE : OFF T= T= T= T= T= T= 26.1 26.1 26.1 26.1 26.1 26.1 ’C ’C ’C ’C ’C ’C Adding date to output FDATE xxx xxx = ON or OFF When FDATE is activated, the current date is output at the beginning of the output line. The date is set with command DATE.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ SERI Serial bus settings SERI b p d s x b p d s x = = = = = bauds (300, 600, 1200, 2400, 4800, 9600) parity (n = none, e = even, o = odd) data bits (7 or 8) stop bits (1 or 2) duplex (H = half, F = full) Giving the command on its own outputs the current settings: >SERI 4800 E 7 1 FDX The settings can be changed one parameter at a time or all parameters at once: >SERI O H 4800 O 7 1 HDX changing parity
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ Td T RH metric units °C °C %RH non-metric units °F °F %RH For example, the command for setting the non-metric units is: >UNIT N Output units : non metric When the command is given with no parameters, the transmitter outputs the currently valid setting. ADDR Setting the transmitter address ADDR aa aa = address (0...99) The address is used when more than one transmitter is connected to one serial bus.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ Operation modes SMODE Setting the serial interface SMODE xxxx xxxx = STOP, RUN or POLL In STOP mode: measurements output only by command, all commands can be used In RUN mode: outputting automatically, only command S can be used In POLL mode: measurements output only with command SEND.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ >OPEN 2 ’DMP nn line opened for operator commands’ >CRH ...
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ PRES Setting the pressure for pressure compensation and ppm calculations PRES pppp.pp pppp.pp = absolute pressure (hPa) If the process pressure differs from the normal ambient pressure, the value has to be entered in the transmitter memory in order to ensure the best possible accuracy. The pressure setting is used for pressure compensation of the DMP248 transmitter.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ XPRES Setting the pressure for pressure compensation and for ppm calculations temporarily XPRES pppp.pp pppp.pp = absolute pressure (hPa) The function and format of XPRES are the same as those of the PRES command except that by using XPRES, the setting is valid only until a reset is given, or power is turned off or pressure is set to zero using XPRES.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ TIME Setting the time TIME For example, to enter a new time: >TIME Current time is 01:35:54 Enter new time (hh:mm:ss) : 13:25:56 When the current time is asked, the new time is passed with . VERS Name and version of the programme VERS For example: >VERS DMP248 / x.yy where x.yy is the programme version. ? Outputting the transmitter settings ? For example: >? DMP248 / 1.
APPENDIX 1 SERIAL COMMANDS __________________________________________________________ ?? Outputting the transmitter settings also in POLL mode ?? Command ?? outputs the same information as command ? but it works also when the transmitter has been set to POLL mode. However, if there are more than one addressed transmitters connected to the serial bus, they all will respond at the same time and the output on the screen will be chaotic.
APPENDIX 2 ________________________________________________________________________ APPENDIX 2 POWER SUPPLY MODULE APPENDIX 2......................................................................................................................................................103 POWER SUPPLY MODULE ..................................................................................................................................104 Installing the power supply module ..........................................
APPENDIX 2 ________________________________________________________________________ Power supply module Installing the power supply module The mains power connection may be connected to the power supply module only by an authorized electrician. A readily accessible disconnect device shall be incorporated in the fixed wiring (IEC 950). Remove the plastic plug in the transmitter housing and replace it with the cable gland.
APPENDIX 2 ________________________________________________________________________ Peel the correct power supply voltage from the sticker enclosed in the power supply module package and attach it on the instrument label to indicate that the supply voltage has been changed. WARNING Do not detach the power supply module from the transmitter when the power is on. WARNING Do not connect the power supply to mains when it is not installed in a DMP248 transmitter.
APPENDIX 3 ________________________________________________________________________ APPENDIX 3 INSTALLING AND USING THE RS 485/422 SERIAL PORT MODULE APPENDIX 3......................................................................................................................................................107 INSTALLATION .................................................................................................................................................108 OPERATION ........................
APPENDIX 3 ________________________________________________________________________ Installation Switch the transmitter off. Resistors R2, R3 and R4 between connectors X4 and X5 in the component board in the cover of the transmitter are removed with side-cutting pliers. The module is plugged in connectors X4 and X5 on the main board of the DMP248 transmitter; connector X1 on the module board to connector X4 and connector X2 to connector X5.
APPENDIX 3 ________________________________________________________________________ connection can be used. No address is needed when only one DMP248 transmitter is used; when several transmitters are connected to the same line, each transmitter must be given an address in the initial configuration. A single transmitter can get its operating voltage from the master or it can have its own (floating) power supply or it has the power supply module in use.
APPENDIX 3 ________________________________________________________________________ The RS 485/422 module has separate lines for transmitting and receiving, but they can be connected together with jumpers. Dual loop connection is the factory setting; when a single loop connection is used, the positions of jumpers in connector X4 on the module must be changed. The HI of the receiving line is approx. 0.6 V and its LO is approx. 0 V in order to reduce noise on the lines when no data is transferred (idling).
APPENDIX 3 ________________________________________________________________________ • Connect wires to the transmitter’s serial connector. • Check the wiring. The following procedure must be repeated with all transmitters. • Open the transmitter cover. • Pull out the RS 485/422 serial port module, if it is already mounted. • Set the serial port of the terminal to 4800 baud, even parity, seven data bits and one stop bit, full duplex (4800 E 7 1 FDX).
APPENDIX 3 ________________________________________________________________________ NOTE The transmitter outputs no prompt (>) after the SMODE POLL command and it only reacts to commands which include its address. • Check that the transmitter responds to its address: >send 22 Td= -47.4 ’C T= 29.1 ’C • Disconnect the terminal. • Check that the jumpers in connector X4 are in the right places. X1 X2 X4 X4 • Remount the RS 485/422 serial module. • Close the cover.
APPENDIX 3 ________________________________________________________________________ RS 232C port of the terminal to connector X17 on the top of the main board and switch the power on. When dual loop is used, the jumpers in connector X4 on the module board must be as shown below. X1 X2 X4 X4 • Set the address of the transmitter, it can be any number between 1 and 99. In this example the address is 22: >addr 22 Address : 22 • Set the serial bus settings according to your system.
APPENDIX 3 ________________________________________________________________________ >send 22 RH= 24.4 %RH T= 29.1 ’C • Disconnect the terminal. • Check that the jumpers in connector X4 are in the right places. X1 X2 X4 X4 • Remount the RS 485/422 serial module. • Close the cover. • Repeat this setting procedure with each transmitter. • When all transmitters on the network have been configured, switch them off.
APPENDIX 3 ________________________________________________________________________ Use command ? to find out the settings of the active transmitter: ? DMP248 / 1.01 CPU serial nr : 0 Keyboard type : 0 Address : 7 Output units : metric Baud P D S : 4800 E 7 1 FDX Serial mode : STOP Output intrv. : 0 min Mtim : 32 Pressure : 1013.25 Analog outputs Ch1 0.00 ... 10.00 V Ch2 0.00 ... 10.00 V Ch1 ( RH ) lo 0.000 %RH Ch1 ( RH ) hi 100.000 %RH Ch2 ( T ) lo -20.000 ’C Ch2 ( T ) hi 180.
APPENDIX 3 ________________________________________________________________________ RS 485 network settings DMP248 settings Full duplex/half duplex Echo on/off single pair HDX OFF dual pair FDX ON Terminal settings Line feed after carriage return HDX/FDX single pair yes FDX dual pair no FDX When terminal is set to general (line feed) after (carriage return), the listings will have two line feeds when also the DMP248 transmitters send line feed.
APPENDIX 4 ________________________________________________________________________ APPENDIX 4 INSTALLING AND USING THE RS 485/422 SERIAL PORT MODULE INSTALLATION .................................................................................................................................... 118 OPERATION ....................................................................................................................................... 118 NETWORK CONFIGURATION .......................................
APPENDIX 4 ________________________________________________________________________ Installation Switch the transmitter off. Resistors R2, R3 and R4 between connectors X4 and X5 in the component board in the cover of the transmitter are removed with side-cutting pliers. The module is plugged in connectors X4 and X5 on the main board of the DMP248 transmitter; connector X1 on the module board to connector X4 and connector X2 to connector X5.
APPENDIX 4 ________________________________________________________________________ NOTE The host computer can restrict the loop supply voltage that can be used; see computer specifications. The serial line structure is a serial interfaced chain (daisy chain). At one end of the serial line there must be a DMP248 transmitter and at the other end a line master. A branch line can be made with a junction box.
APPENDIX 4 ________________________________________________________________________ simpler wiring. Data transmission is achieved by switching the loop current on and off. Normally, current flows through the loop(s) even when the DMP248 transmitter is not on, so switching one transmitter off does not affect the other transmitters on the loop. When the wires have been connected correctly, the voltage drop from RX+ to RX- is below 2 V.
APPENDIX 4 ________________________________________________________________________ • Set the serial port of the terminal to 4800 baud, even parity, seven data bits and one stop bit, full duplex (4800 E 7 1 FDX). • The serial settings of the transmitter must also be 4800 E 7 1 FDX and the transmitter must be in STOP mode. If these factory settings have been changed, they must be changed back. Connect the RS 232C port of the terminal to connector X17 on the top of the main board and switch the power on.
APPENDIX 4 ________________________________________________________________________ • Check that the transmitter responds to its address: send 22 Td= -47.4 ’C T= 29.1 ’C • Disconnect the terminal. • Remount the digital current loop module. • Close the cover. • When all transmitters on the network have been configured, switch them off. Dual loop operation Single pair/dual pair use is configured through wiring (see figure on page 2). The following procedure must be repeated with all transmitters.
APPENDIX 4 ________________________________________________________________________ Dual loop wiring • Set the address of the transmitter, it can be any number between 1 and 99. In this example the address is 22: >addr 22 Address : 22 • Set the serial bus settings according to your system.
APPENDIX 4 ________________________________________________________________________ Checking the serial port network operation Normally, measurement readings are asked when the transmitter is in POLL mode; then the command must include the address of the transmitter. If the settings of the transmitter need to be changed, the transmitter is switched to STOP mode with command OPEN; commands can then be given without address. When the line to the transmitter is closed, it returns to POLL mode.
APPENDIX 4 ________________________________________________________________________ When the necessary settings have been given, close the line to transmitters (the command closes all open lines): >close line closed CLOSE command is always given without address. If no lines are open, there will be no response to the CLOSE command. POLL mode If a transmitter has been set to POLL mode, it will respond only to commands which include its address: send 22 Td= -47.4 ’C T= 29.
APPENDIX 4 ________________________________________________________________________ Specifications Galvanic isolation Loop supply voltage Loop supply current must be current limited Operating loop voltage requirement Loop current Connections on the main board Assembly Board dimensions Operating mode (single or dual pair wiring) Network: network type cable type line length max. number of devices data speed operating mode isolation voltage proof Operating temperature Storage temperature 1500 VAC/DC max.
APPENDIX 5 ________________________________________________________________________ APPENDIX 5 ERROR MESSAGES APPENDIX 5......................................................................................................................................................127 ERROR MESSAGES ............................................................................................................................................128 Errors after reset ..........................................................
APPENDIX 5 ________________________________________________________________________ ERROR MESSAGES The DMP248 transmitters go through a self-diagnostics procedure when the power is switched on. When the procedure does not reveal any errors or faults, the transmitter starts operating normally. If errors or faults are found, the transmitter outputs an error message. The error messages can be divided into two groups: error messages after the reset and error messages during operation.
APPENDIX 5 ________________________________________________________________________ l CPU EEPROM error l input hybrid error Errors during operation Two types of errors are possible during operation of the transmitters. The first type indicates that no frequency comes from the converter.
APPENDIX 5 ________________________________________________________________________ The LEDs display these error types as follows: no frequency at all a frequency missing from the RH channel a frequency missing from the T channel The second error type indicates erroneous y-values (used in internal calculations): Display: Serial bus: E51 T y-value out of range E53 U1 y-value out of range The LEDs display these error types as follows: RH channel y-value out of range T channel
APPENDIX 6 ________________________________________________________________________ APPENDIX 6
APPENDIX 7 ________________________________________________________________________ APPENDIX 7 Alarm output unit The alarm output unit consists of two alarm relays and two optoisolated outputs (see Figure 1). The relay output 1 is available at screw terminal X1 and the relay output 2 at screw terminal X2. The optooutputs are activated simultaneously with the corresponding relays and available at screw terminal X5. OPTIONS: ALARM 1 ALARM 2 X1 C NONC CNONC X2 SPCO relay outputs max.
APPENDIX 7 ________________________________________________________________________ side of the module if the mains power is in use. Attach the ribbon cable from X3 of the alarm unit to the X16 on the main board of the transmitter. NOTE NO jumper in connector X4 during normal operation. When one alarm unit relay is on, the corresponding LED is lit.
APPENDIX 7 ________________________________________________________________________ Setting and activating the outputs with menu commands Disconnect the security lock jumper! • Select MORE in the main menu and then ALARM; the following is displayed: • If the settings need to be changed, press CL: - the quantity starts blinking; it can be changed with arrow switches, and acknowledged with ENT. - the third parameter (in this example HI ON) starts blinking.
APPENDIX 7 ________________________________________________________________________ Setting and activating the outputs using an RS line Disconnect the security lock jumper! ALARM or ALARM n ON where n = channel number (1 or 2) The currently valid settings of the alarm output unit can be checked with command ALARM: >alarm Ch1 RH LO Ch2 RH HI OFF OFF 0.00 100.00 0.00 %RH 0.00 %RH > This is an example of the factory setting (both alarm outputs are in OFF mode, i.e. not in use).
APPENDIX 7 ________________________________________________________________________ When the alarm outputs have been set, you can activate the outputs with commands ALARM 1 ON (channel 1) or ALARM 2 ON (channel 2). Note that you can also activate the outputs when giving other parameters with command ALARM. Examples of activating the outputs: with command ALARM: >alarm Ch1 Td Ch2 RH > 1 HI HI Td ON ON HI -20 -20.00 100.00 5 5.00 ’C 0.
APPENDIX 8_________________________________________________________________________ APPENDIX 8 Pressure conversion chart Multiplication factors NOTE: conversions from mmHg and inHg are defined at 0°C and for mmH2O and inH2O at 4°C. FROM: TO: hPa/mbar 0.01 PaN/m2 mmHg torr 1.333224 33.86388 inHg 0.09806650 mmH2O 2.490889 inH2O 1013.25 atm 980.665 at 1000 bar 68.94757 psi psia = psi absolute Example: 29.9213 inHg = 29.9213 x 33.86388 = 1013.
