User Guide

DigiGauge Digital Pressure Gauge
Instruction Manual
Page 4
Calibration
Each DigiGauge instrument is fully calibrated during manufacture and certificates of calibration may be requested at time of order-
ing. It is recommended that the calibration of the gauge should be checked against a known standard every 12 months or at inter-
vals specified by relevant quality assurance procedures. British Rototherm offers a rapid in-house recalibration service for its
pressure measurement products, traceable to national standards. Please contact the Sales Office for details.
Note that calibration is made easier by operating the gauge at the 0.5 second update rate which allows adjustments to be made
more quickly.
To zero the gauge
1. Ensure that there is no pressure applied to the gauge.
2. Some versions of the DigiGauge may be fitted with an optional multiturn potentiometer for zero adjustment. If the zero
potentiometer is fitted (marked ZERO on the printed circuit board) turn the adjustment screw until the display shows a
reading of 0000. Turn the screw clockwise to increase the reading on the display, or anticlockwise to decrease. If no
potentiometer is fitted adjust the zero using the procedure given in steps 3 to 5 below.
3. On the bank of dual-in-line (DIL) switches, (marked SW1-4 on the printed circuit board), move switch SW4 (marked 4 on
the switch) to the ON position (move the switch from its left-most position to the right most position). The gauge will
display ZERO.
4. Hold down the middle push-button switch (marked SW6 on the printed circuit board) until the display shows Std.Z.
Release the middle push-button switch.
5. The gauge will now display ZERO once more. Move the DIL switch SW4 back to the original position (move the switch
from the right-most position to the left-most position). The gauge is now zeroed.
To set the correct span
1. Prior to span adjustment the gauge should be zeroed if necessary.
2. Apply full scale pressure to the gauge. The full-scale pressure rating (in bar) is marked on the dial or label attached to
the case.
3. With full scale pressure applied, adjust the potentiometer marked SPAN on the printed circuit board until the display
reading is equal to the full scale value. Turning the screw clockwise will increase the reading on the display, turning the
screw anticlockwise will decrease it.
To linearise the gauge
The procedure for linearisation depends on whether the gauge reads only positive pressures or is a compound type reading vacu-
um as well.
1. Apply precisely half of the maximum rated pressure to the gauge.
2. Move DIL switch SW3 to the ON position (move from the left most position to the right-most position). The display will
now read Lin.
3. If the gauge reads only positive pressures proceed to 4. below. If the gauge is a compound type proceed to 6. below.
4. Hold down push button switch SW6 until the display reads Std.L then release switch SW6. The display will then show
Lin once more.
5. Return DIL switch SW3 to its original position. The gauge is now correctly linearised.
6. For compound gauges move DIL switch SW1 to the ON position and SW2 to the OFF position. The display will now read
Lin.P.
7. Hold down push button switch SW6 until the display reads St.LP then release switch SW6. The display will then show
Lin.P once more.
8. Move DIL switch SW1 to the OFF position and SW2 to the ON position. The display will now read Lin.n.
9. Apply precisely 0.750 bar of vacuum (-0.750 bar gauge) to the gauge. Hold down push button switch SW6 until the dis
play reads St.Ln then release switch SW6. The display will then show Lin.n once more.
10. Return DIL switch SW3 to the OFF position and SW1 & SW2 to their original positions. The compound gauge is now
correctly linearised.