ENMET Corporation PO Box 979 Ann Arbor, MI 48106-0979 ISA – M OPERATION & M AINTENANCE M ANUAL 80003-027 04/27/95 MCN-204, 10/20/98 MCN-285, 11/20/02
Table of Contents 1.0 INTRODUCTION................................................................................................................................1 1.1 Unpack................................................................................................................................................................................ 1 1.2 Check Order................................................................................................................................................
ISA – M ENMET Corporation 1.0 Introduction The ENMET Model ISA-M detector/alarm is an all solid-state electronic gas-detecting instrument that minimizes the risk of harm or death to people who are exposed to potentially hazardous gas environments. It continuously monitors for combustible or toxic gases and warns of a dangerous gas situation with enough time to take action to avoid harm. Audio (horn) and visual (light) alarms are calibrated to trigger at both high and low level gas concentrations.
ENMET Corporation ISA – M 2.0 Features if the ISA – M 2.1 External Feature of the ISA – M Figure 1 shows the ISA-M control unit which contains the electronic circuitry and controls. Main features are listed below. Feature Description Meter This is a non-linear device. Do not infer exact readings from unmarked regions of the meter scale. The scale is marked in units of measure for the gas depending on instrument calibration.
ISA – M ENMET Corporation 2.2 Internal Features of the ISA – M Figure 2 shows the circuit board and terminal blocks housed inside the hinged oiltight control unit. Specific relays and adjustments are defined in the table below. Feature Description Internal Relay Contacts There is one relay for each alarm level. Relays can be used to activate an external remote alarm signal when a hazardous gas level is detected, or when the ac or dc power is interrupted.
ENMET Corporation ISA – M 4.0 Installation The ISA – M is completely oiltight. Use the correct oiltight fitting for the cord or conduit when supplying power to the unit. NOTE: This instrument is NOT rated for hazardous locations. The instrument must be located in a NON-Hazardous area. 4.1 Mounting and Power Hook-up Figure 3: Mounting Dimensions of the ISA – M 1. 2. A 110 VAC line cord is supplied, plug this into an appropriate outlet.
ISA – M ENMET Corporation 4.2 Sensor Location Gases have different densities. Some are heavier than air and concentrate at the bottom of a space. Some are lighter than air and gather at the top. Consider the density of the gas you want the sensor to detect when you install the sensor. Some examples are given below. Table 1: Heavier than Air Gas Sensor Location Bottled LP (liquefied petroleum) Propane Interior wall; 18-24" from floor.
ENMET Corporation ISA – M 4.3 Sensor Hook-up The MOS sensor is connected to the ISA-M control unit with three conductor wiring, use the correct oiltight fitting. Two conductors supply heater current to the sensor. The third conductor is a signal wire. Size of heater wire depends on the distance between the particular sensor and the control unit. See Table 4.
ISA – M ENMET Corporation 4.4 Sensor Heater Voltage Heating the sensor promotes the oxidation reaction on the element surface. The temperature to which the sensor element is heated determines the selectivity of the equipment to certain gases. A chart, located inside the instrument front cover, specifies the voltage for the sensor. Units requiring purging have two voltages specified. Refer to Figure 2 for potentiometer locations.
ENMET Corporation ISA – M 5.0 Operation Mount and install the ISA – M electronics unit and sensor as outlined in the previous section (4.0). NOTE: There is no ON/OFF switch on the unit. As a safety device, this unit is designed to be powered and ON at all times. 5.1 Warm – Up 1. Turn the switch to PURGE O N (when applicable) or H ORN O FF. 2.
ISA – M ENMET Corporation 6.0 Routine Gas Test and Recalibration Perform this test at regular intervals, you decide how often; we recommend that you do it at least every six weeks. NOTE: The gases should be identical, or equivalent (correlation gas) to those used to initially calibrate the unit, unless you want to recalibrate to a new gas or different concentration. In addition, calibration gases must be in a background of air; do not use gases with an inert gas background (such as nitrogen or argon). 6.
ENMET Corporation ISA – M Table 5: Approximate Alarm Time Gas or Vapor 20 ppm CO 50 ppm CO 200 ppm CO 10% LEL methane 20% LEL methane 100 ppm vinyl chloride typical hydrocarbon vapors 20% LEL propane Time to Alarm 5 - 7 minutes 5 minutes 2 minutes 1 minute 1 minute 1 - 2 minutes 1 - 2 minutes 1 minute 8. After you verify the alarm response, turn the gas off and remove the calibration fixture from the gas cylinder. 9. Turn the switch back to OPERATE.
ISA – M ENMET Corporation 7.0 Maintenance The ISA – M gas monitor is a safety instrument and requires periodic testing and calibration at regular intervals. In addition, check for obvious mechanical damage or malfunctions such as burned out lamps. On units requiring purging, purge the sensor periodically. This interval varies with the amount of contaminants in the atmosphere. 4.1 Basic Troubleshooting Symptom Problem/Correction When first plugged in, the unit alarms for up to 10 - 20 minutes.
ENMET Corporation ISA – M 7.3 Replacement Part Numbers ENMET replacement part numbers: Description Part Number Meter Lamp body Lens, red Lens, green Lens, amber Control unit light bulb Accessory Case Calibration adapter Cylinder of calibration gas 03411-000 62012-010 62012-011 62012-012 62012-013 63001-002 73083-000 03700-001 Contact ENMET for part number of target gas for each instrument. See note below.
ISA – M ENMET Corporation 9.0 WARRANTY ENMET warrants new instruments to be free from defects in workmanship and material under normal use for a period of one year from date of shipment from ENMET. The warranty covers both parts and labor excluding instrument calibration and expendable parts such as calibration gas, filters, batteries, etc... Equipment believed to be defective should be returned to ENMET within the warranty period (transportation prepaid) for inspection.
