Bacharach 2772-0803 6. Stepping Clamp Vertical, 7. Summary of Gate & Step Values, Changing A Pump

REMOTE INTELLIGENT SENSOR - AREA MONITOR

NOTE: If it is not possible to achieve a satisfactory average tape step length, please refer to additional information in Section 4.21.2.

Figure 4-6. Stepping Clamp Vertical

With the stepping cam vertical, and gate opening lever in the gate closed position, the optics block can be replaced and the two screws put in loosely. Position the optics block so that there is a gap of 0.020" to 0.040" (0.5mm to 1.0mm) between the two halves of the gate.

Ensure that the gap is parallel when it is

measured. Note that the plastic tubes connecting the moving part can cause it to twist a little in its pivot. This can make the gap closer at the top or the bottom.

After initially setting the gap, tighten the block fixing screws to lock the optics block in position. Replace the connector (with the switch ‘off ’), then, verify that the tape steps correctly as follows.

Place a length of tape in the gate. This can be done by pulling a length out of a cassette which can be placed on top of the unit, or held in one hand.

Avoid touching tape with bare fingers. Switch ‘on’, and press the tape reset button to

step on the tape. Mark the edge of the block on the tape with a pencil. Repeat the process until 4 or 5 steps are marked on the tape. Measure the length of the tape steps and take an average. The average step should be between 0.27" and 0.32", (7 to 8 mm).

If the steps are much longer, the cassette life will be less than the quoted 30-day maximum. In this case, the position of the optics block may be adjusted by repeating the above process, but reducing the gap gradually. Continue until a tape step of approximately 0.32"(8 mm) is achieved. Do not reduce the gap to less than 0.020" (0.5 mm) or tape drag in the gate may occur. This condition may be aggravated if the tape gets damp. Tape breakage can occur under these conditions.

NOTE: In some cases it may not be possible to reduce the tape gap below about 0.030" (0.75 mm), in this case leave it set at that value.

Figure 4-7. Summary of Gate & Step Values

4.10.7WHAT TO DO IF CLEANING DOES NOT RECTIFY THE PROBLEM. If performance cannot be improved, or if the change is marginal, it will be necessary to replace the optics block. A new optics block can be ordered from your distributor. When ordering the replacement block, specify the RIS system gas type and range, also the serial number. This information will ensure that the correct item is supplied.

It should be appreciated that if the block is replaced the original calibration of the instrument is no longer valid. It may be assumed that, because of manufacturing methods and testing, performance with a replacement block will be within 10% of the original. Factory re-calibration against gas is recom- mended as soon as is practicable.

A replacement block carried as a spare against future need is a wise precaution for those applica- tions where contamination of the input tube and optics block is a problem.

4.11 CHANGING A PUMP

Providing that care is taken, this is not a difficult procedure.

4.11.1PREPARATION. Have available a replace- ment pump of the correct type. RIS systems with a Flow Rate of 200 mL/min. or less are fitted with the low flow pump and RIS’s with a Flow Rate higher than 200 mL/min. are fitted with the high flow pump. These catalog numbers specify the pump complete with mounting bracket ready to fit.

Warn that the system is being taken out of

operation and that alarms may be activated during the work. Remove external power from the RIS, open the door and turn off SW1.

Instruction 2772-0803 Page 4-5