Detcon DM-634 User Manual

Page 8

Ventilation - Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a

manner where the migration of gas clouds is quickly detected.

Personnel Exposure - The undetected migration of gas clouds should not be allowed to approach concentrated per-

sonnel areas such as control rooms, maintenance or warehouse buildings. A more general and applicable thought

toward selecting sensor location is combining leak source and perimeter protection in the best possible configuration.

Note: In all installations, the sensor points down relative to grade (Fig. 1). Improper sensor orientation may result

in false reading and permanent sensor damage.

3.5.3 Local Electrical Codes

Sensor and transmitter assemblies should be installed in accordance with all local electrical codes. Use appropriate

conduit seals. Drains & breathers are recommended. The sensor assemblies are designed to meet NEC and CSA

requirements for Class I; Groups B, C, D; Div. 1 environments.

3.5.4 Accessibility

Consideration should be given to easy access by maintenance personnel as well as the consequences of close prox-

imity to contaminants that may foul the sensor prematurely.

Note: An appropriate conduit seal must be located within 18" of the sensor assembly. Crouse Hinds type EYS2,

EYD2 or equivalent are suitable for this purpose.

3.5.5 Installation Procedure

Remove the junction box cover and un-plug the control circuit by grasping the two thumb screws and pulling

outward.

Securely mount the sensor junction box in accordance with recommended practice. See dimensional drawing (Fig. 2).

Observing correct polarity, terminate 3 conductor field wiring, RS-485 wiring, and applicable alarm wiring to the

sensor base connector board in accordance with the detail shown in Figure 3. Normally open and normally closed

Form C dry contacts (rated 5 amp @ 120VAC; 5 amp @ 30VDC) are provided for Fault, Alarm 1, and Alarm 2.

Position gold plated jumper tabs located on the connector board in accordance with desired Form C dry con-

tact outputs: NO = Normally Open; NC = Normally closed (see f igure 3).

Note: If a voltage signal output is desired in place of the 4-20mA output, a 1/4 watt resistor must be installed

in position R1 of the terminal board. A 250

Ω resistor will provide a 1-5V output (– to mA). A 100Ω resistor will

provide a .4-2V output, etc. This linear signal corresponds to 0-100% of scale (see f igure 3).

Program the alarms via the gold plated jumper tab positions located on the CPU board (see f igure 4). Alarm 1

and Alarm 2 have three jumper programmable functions: latching/non-latching relays, normally energized/nor-

mally de-energized relays, and ascending/descending alarm set points.

The fault alarm has two jumper programmable functions: latching/non-latching relay, and normally

Detcon Model DM-634 Oxygen Sensor PG.8

EYS

Seal

Fitting

Drain

“T”

Plug any unused ports.

Figure #1