Det-Tronics PIR9400 PointWatch Infrared Hydrocarbon Gas Detector User Manual

Page 17

95-8440

9.3

CALIBRATION

The PointWatch Detector is factory calibrated for

methane and, unlike catalytic detectors, does not

require routine calibration to ensure proper operation.

Guidelines for when calibration or bump tests should
be performed/ checked are listed in Table

NOTE

To check calibration, inhibit output loads as
necessary, then apply

50%

LFL calibration gas to

the detector using the equipment provided in the
calibration kit. Ensure that the correct calibration
gas is used. Check the current output for the
appropriate response (

mA).

NOTE

Drift will be indicated by a constant zero offset in
one direction either above or below

mA. The

presence of background gas would be indicated
by a small but constantly changing output.

CaLIBRaTION EqUIPMENT
The following equipment is required to calibrate the

PointWatch Detector (calibration kits from Det-Tronics

contain all items below):

–

50%

LFL calibration gas

–

Calibration nozzle (for aluminum model)

–

Regulator (minimum

2.5

liter/minute flow rate)

–

Three feet of tubing.

CaLIBRaTION PROCEDURES
The procedures in this section explain calibration

sequences for both stand alone PointWatch Detector

applications (when a user supplied or no termination box

is used) and for applications where the detector is used

with the Det-Tronics supplied termination box (containing

a magnetic reed switch and LED). For applications where
the PointWatch Detector is used with the Infiniti U

9500

Transmitter or the Eagle System, refer to those instruction

manuals for the calibration procedure.

When the Model PIR

9400

Detector is used in a

stand-alone configuration or with transmitters and

controllers other than those supplied by Det-Tronics, the

current loop output must be monitored in order to calibrate

(for both inhibited and live current loop configurations).

When the detector is used with a Det-Tronics termination

box, the magnetic switch and LED in the termination

box are used to initiate and annunciate the calibration

sequence. The current loop output also indicates the

calibration sequence (for both inhibited and live current

loop configurations).

iMPoRtant CaLiBRation notES

• Ensure that the detector has been operating for at

least two hours before calibrating.

• Do not open the explosion-proof enclosure when

power is applied to the system unless the appropriate
permits have been procured.

• The calibration gas used must be the same as the gas

selected on the Gas Selection Switch. The factory
setting is for methane, so use methane to calibrate
if the Gas Selection Switch is set in position “

.” If

the Gas Selection Switch is set in any other position,
ensure that the correct gas is used to calibrate. See
Figure

. Only

50%

LFL calibration gas can be

used to calibrate the PointWatch Detector.

• If the detector is being used in a stand alone

configuration, the use of an inhibited current loop
is recommended. Live current loop calibration was
designed primarily for use with the Infiniti U

9500

Transmitter or the EQP system. Accomplishing live
current loop calibration manually is possible but
not recommended. Instructions for live current
loop calibration are provided after the “Calibration
Procedure - Inhibited Current Output During
Calibration” procedure.

Table 3—Calibrate or Check

Function

Calibrate Check

Startup

Gas selection switch changed

Non-standard gas

(using linearization other than methane)

Replace any part

Constant zero offset

Periodic Functional Testing

(at least once a year)