ENMET Corporation PO Box 979 Ann Arbor, MI 48106-0979 ISA-44-2-OD OPERATION & MAINTENANCE MANUAL 80003-007 Revised June 1992 MCN-122; 09/01/92 MCN-204; 01/29/01 MCN-295; 09/04/03
Table of Contents 1.0 INTRODUCTION................................................................................................................................1 1.1 Unpack................................................................................................................................................................................ 1 1.2 Check Order................................................................................................................................................
ISA-44-2-OD ENMET Corporation 1.0 Introduction ENMET model ISA-44-2-OD is an all solid-state electronic gas detection system that minimizes the risk of injury or death to people who are exposed to potentially hazardous gas and/or oxygen deficiency in working environments. It continuously monitors for combustible gas, toxic gas, and lack of oxygen. Whenever the situation becomes threatening, alarms are triggered alerting all personnel in potential danger to take proper action.
ENMET Corporation ISA-44-2-OD 2.0 Features and Controls of the ISA-44-2-OD How the ISA-44-2-OD Works The ISA-44-2-OD uses gas-sensitive Metallic Oxide Semiconductor (MOS) sensing elements that react to toxic and combustible gas molecules. An oxidation reaction occurs on the sensor surface when contaminants are present. The oxidation reaction changes the gas sensor's electrical resistance, which then triggers the alarm circuitry when the concentration of gas goes beyond a preset level.
ISA-44-2-OD ENMET Corporation 2.2 External Features See Figure 1 for the outside front panel of the instrument: Feature Description Power Indictor (Green Light) When the green light for a channel is on, the unit is operating normally; that is, there is no alarm condition. When this light is off, the channel is in alarm or the power to the channel has been interrupted. Visual Alarms Red Light: Visual alarm signal for high-level gas concentration.
ENMET Corporation ISA-44-2-OD 2.3 Internal Circuitry of the ISA-44-2-OD See Figure 2, 3 and 4 for interior location of ISA-44-2-OD circuit boards, terminal blocks, etc. Feature Description Relay Outputs For both high and low-level alarms (TB1, TB3, TB4). Relays can activate a remote alarm signal when either a hazardous gas or oxygen deficiency level is detected or when the AC or DC power is interrupted. There are five double-pole relays.
ISA-44-2-OD ENMET Corporation O2 Alarm Adjust R52 (–)O2 Sensor Green Wire from ISB COM. (+)O2 Sensor Orange Wire from ISB TB3 Relay K3 TP1 Red TP3 Red N.O. N.C. O2 Channel Relay R48 TB2 TP2 Red Low Level Set Full Scale Adjust R19 R46 R44 Null Adjust Purge Adjust Heater Adjust R1 Low Alarm Set Meter Adjust R4 R2 TP5 Red TP4 Black R3 COM. N.O. COM. Channel 1 High Relay N.C. Relay K2 N.O. TB1 Relay K1 N.C.
115 V AC LOW 115 V AC HIGH ISA-44-2-OD Chassis Ground ENMET Corporation TB6 TB5 +12 VDC Purge Adjust R37 DC Ground Heater Adjust R1 Low Alarm Set Meter Adjust R2 Sensor Heater Orange Wire R3 Sensor Ground Brown Wire R4 TP1 Red TP2 Black High Alarm Set Channel 3 High Relay COM. N.O. N.C. Relay K5 COM. N.O. TB4 N.C.
ISA-44-2-OD ENMET Corporation 3.0 Installation The ISA-44-2-OD is completely oiltight and watertight. Use the correct watertight fitting for the cord or conduit when supplying power to the unit. 3.1 Power Hook-Up and Mounting of Control Unit ISA-44-2-OD 1. Choose a suitable location for mounting the electronics control unit. 2. 3. The OPERATE switch should be in the HORN OFF position. Open the control unit. Remove the terminal strip cover from TB-6 (see Figure 2 and 4).
ENMET Corporation ISA-44-2-OD 3.2 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. As a guide, consult the gas descriptions below.
ISA-44-2-OD ENMET Corporation 3.3 Sensor Hook-up The oxygen cell comes packaged in a sealed vapor proof bag. The cell needs to be installed in the remote sensor enclosure after the enclosure has been mounted. See Figure 6. This procedure is the same as the procedure described in Section 5.3 The MOS sensor is connected to the ISA-44-2-OD 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.
ENMET Corporation ISA-44-2-OD Relay Hook-up See Figure 8 for an example of how to use the relay contacts.
ISA-44-2-OD ENMET Corporation 3.4 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 panel, specifies the voltage for each sensor. Refer to Figures 3 and 4 for potentiometer locations. NOTE: Do not increase any sensor voltage to values greater than those given on the chart.
ENMET Corporation ISA-44-2-OD 4.0 Operation Mount and install the ISA-44-2-OD electronics unit and sensors as outlined in the previous Section. NOTE: There is no ON/OFF switch. As a safety device this unit is designed to be powered and ON at all times. 4.1 Warm-Up 1. Turn the switch to PURGE O N (when applicable) or H ORN O FF. 2.
ISA-44-2-OD ENMET Corporation 4.4 Rough Test To see that the instrument is capable of alarming, at a quick glance. Do not substitute this procedure for regular calibration with proper equipment. For hydrocarbon (combustible) responses: Hold a butane lighter near the sensor cover. Briefly depress the lever, without striking the flint, to squirt some butane vapors. Do not squirt butane vapors directly on the sensor. The alarm should trigger; green power light goes off and the red light and horn activate.
ENMET Corporation ISA-44-2-OD 5.0 Maintenance The ISA-44-2-OD hazardous gas and oxygen deficiency monitor is a safety instrument and requires periodic testing and recalibration at regular intervals. Also, check for obvious mechanical damage or malfunctions such as burned out lamps. Purge the sensor periodically. This interval varies with the amount of contaminants in the atmosphere. 5.1 Routine Gas Test Perform this test at regular intervals.
ISA-44-2-OD 7. ENMET Corporation Put the cal cup of the calibration fixture over the sensor. Let the gas flow over the sensor until the alarm triggers. Use Table 6 for the approximate allowable time period until alarm: Table 7: 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.
ENMET Corporation ISA-44-2-OD 5.2 Calibration 5.2.1 Toxic Gas Channel # 1 The following procedure is for checking the calibration level and for recalibrating the Carbon Monoxide(CO) Channel of the ISA-44RAL-OD. Refer to Figure 2 and 4. Perform A Complete Recalibration Periodically (at least monthly) and: • When you replace the sensor. • When the sensor encounters severe conditions (i.e., gross exposure to smoke or liquid hydrocarbon).
ISA-44-2-OD ENMET Corporation NOTE: If amber light is on prior to POT adjustment, adjust this POT CW until light is off, then readjust CCW until light just activates. IMPORTANT : The meter may not display the exact low level alarm. DO NOT change the low level alarm meter reading unless grossly off (four meter needle widths or more). If far off, recalibrate the high alarm, meter reading (step 9). 15. Repeat step 11. 16. Repeat step 12. 17. Reconnect the sample head to the air line. 18.
ENMET Corporation ISA-44-2-OD 5.2.2 Oxygen Channel # 2 This procedure is given in reference to an S-2 cell, which is ENMET P/N 67013-008 as furnished as a replacement cell. MATERIALS § digital voltmeter § small screwdriver PROCEDURE 1. Turn OPERATION switch to HORN O FF position. 2. Null Adjust a. Disconnect the oxygen cell from the circuit by disconnecting leads at TB3-8 (+) (terminal block 3-position 8) and/or TB3-9 (-). Removing one lead is sufficient to break the circuit. See Figure 3. b.
ISA-44-2-OD ENMET Corporation 5.2.3 Combustible Gas Channel # 3 1. Wait 8 - 10 minutes for the sensor to recover from the test. 2. Repeat steps 3 - 7 as outlined in the test procedure above using the high level calibration gas. 3. With the gas still flowing, adjust the Meter Adjust potentiometer (Ref. Figure 4) R33; ccw to increase, cw to decrease meter reading) with a small screwdriver. • You want to have the meter pass through the low level alarm point, to verify that the alarm light triggers.
ENMET Corporation ISA-44-2-OD 5.3 Replacement of Sensors Gas Sensors The MOS sensor is durable, it can be purged of contaminants by operating in PURGE for a sufficient length of time and at regular intervals. Gross contamination usually occurs during unavoidable misuse. Close exposure to an open gas flame, dipping the sensor in a hydrocarbon such as lacquer, or continuous exposure to heavy concentrations of industrial vapors will grossly contaminate a sensor.
ISA-44-2-OD ENMET Corporation 5.4 Trouble Shooting Symptom Problem/Correction When first plugged in, the unit alarms for up to 10 - 20 minutes. If the unit has not been used recently, this is normal. The MOS sensor is cold and/or contaminated. Keep unit ON or PURGE (on units so equipped) overnight with the sensor in fresh air. Red alarm light stays on continuously, even after allowed to operate (or PURGED) overnight.
ENMET Corporation ISA-44-2-OD 6.
ISA-44-2-OD ENMET Corporation 8.0 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.
ENMET Corporation ISA-44-2-OD Notes: 24
PO Box 979 680 Fairfield Court Ann Arbor, Michigan 48106-0979 734.761.1270 Fax 734.761.3220 Returning an Instrument for Repair ENMET instruments may be returned to the factory or any one of our Field Service Centers for regular repair service or calibration. The ENMET Repair Department and Field Service Centers also perform warranty service work.
Repair Return Form Mailing Address: ENMET Corporation PO Box 979 Ann Arbor, Michigan 48106 Phone Number: FAX Number: Shipping Address: ENMET Corporation Attn: Repair Departme nt 680 Fairfield Court Ann Arbor, Michigan 48108 734.761.1270 734.761.
