Det-Tronics PIRECL Infrared Hydrocarbon Gas Detector PointWatch Eclipse - Manual (Page 18)

16 95-8526 14.2
reMote Calibration option
In most applications, it is recommended to install the
Pointwatch Eclipse where it will contact the vapor of
interest as quickly as possible. Unfortunately, the best
location for early warning can often result in accessibility
problems for the operator when calibration is required.
In these applications, the Model PIRTB Termination Box
is highly recommended to provide the ability to calibrate
the Pointwatch Eclipse from a remote location.
The PIRTB consists of a termination/circuit board, housed
within an explosion-proof junction box. The circuit board
contains a magnetic reed switch for initiating calibration,
an indicating LED to signal the operator when to apply
and remove the calibration gas, and a wiring terminal
block. The junction box cover is furnished with a small
viewing window that enables calibration to be performed
without hazardous area de-classification. The PIRTB may
be installed up to 100 feet away from the Eclipse. Refer
to Figure 21 for remote calibration configuration options.
NOTE
The remote calibration switch is intended for
initiating calibration only. Resetting latching alarm
outputs using the remote calibration switch cannot
be accomplished without entering the Calibration
mode.
The following recommendations are provided to enhance
operator ease and convenience of remote calibration
configurations:
1. Install the Eclipse in such a manner that the onboard
LED is visible whenever possible. This will aid in
checking device status "at a glance."
2. The Eclipse is provided with a calibration gas nozzle
on the weather baffle, which allows the use of
permanently attached calibration gas delivery tubing
(either polyethylene or stainless steel). The tubing is
typically routed in parallel with the remote calibration
cabling to the same location as the PIRTB termination
box. This arrangement enables a technician to
initiate calibration and deliver the calibration gas to
the Eclipse from a single location.
3. When permanently installed calibration gas tubing
is utilized, always install a shut-off valve at the open
end to prevent unwanted vapors or debris from
entering the tubing.
4. Always purge the permanent tubing with clean,
dry compressed air prior to and immediately after
calibration to ensure that residual combustible
gases are cleared. Always close the shutoff valve
after post-calibration purging is complete. This will
ensure that all hydrocarbon vapors are eliminated
from the Eclipse optics.
5. Note that permanently installed calibration gas tubing
will increase the calibration gas consumption rate as
a function of total tubing length.
Other methods of remote Eclipse calibration include
utilizing HART or MODBUS communications. Refer to
the HART and MODBUS appendices for details.
SpeCial appliCationS
The standard Pointwatch Eclipse is intended for
open area combustible gas detection applications.
However, special detector configurations are available
for applications such as duct-mounting and sample
extraction. Contact Detector Electronics Corporation for
information on these special device configurations.