Analytical Industries GPR-7500 AIS Trace PPM Hydrogen Sulfide Analyzer - Manual (Page 7)

Advanced Instruments, Inc.
7
Application, Positive-Pressure A flow indicator with integral metering valve positioned
upstream of the sensor is recommended for controlling the sample flow rate between 1-5 SCFH. If a
separate flow control valve and a flow indicator is used, position flow control valve upstream of the sensor
and position a flow indicator downstream of the sensor. If necessary, a pressure regulator upstream of the
flow control valve should be used to regulate the inlet pressure between 5-30 psig.
Flow rates of 1-5 SCFH cause no appreciable change in the H
2
S reading. However, flow rates above 5
SCFH may generate a slight backpressure on the sensor resulting in erroneous readings.
Caution: Do not place your finger over the vent (it pressurizes the sensor) to test the flow indicator when
gas is flowing to the sensor. Removing your finger (the restriction) generates a vacuum on the sensor and
may damage the sensor (voiding the sensor warranty).
Caution: If the analyzer is equipped with a coalescing filter as part of an optional sample
conditioning system, inlet pressure must not exceed 30 psig.
Application, Atmospheric or Slightly Negative-Pressure: For such measurements,
an optional external sample pump may be used upstream of the sensor to push the sample across the
sensor and out to atmosphere. However, if the sample pump can pull/push more than 5 SCFH, a flow
control must be used to control the sample flow. The flow control valve must be positioned in such a way
that it does not generate any vacuum on the sensor.
Caution: If the analyzer is equipped with a flow indicator with integral metering valve or a
metering flow control valve upstream of the sensor and the pump is installed downstream of
sensor- open the metering valve completely before turning the pump ON to avoid drawing a
vacuum on the sensor and placing an undue burden on the pump.
If pump loading is a consideration, a second throttle valve on the pump’s inlet side may be necessary to
provide a bypass path so the sample flow rate is within the above parameters.
Moisture & Particulates: Installation of a suitable coalescing or particulate filter is required to
remove condensation, moisture and/or particulates from the sample gas to prevent erroneous analysis
readings and damage to the sensor or other optional components. Moisture and/or particulates do not
necessarily damage the sensor. However, collection of moisture/particulate on the sensing surface can
block or inhibit the diffusion of sample gas into the sensor resulting in a reduction of sensor signal output
and the appearance of a sensor failure. Consult factory for recommendations concerning the proper
selection and installation of optional components.
Moisture and/or particulates generally can be removed from the sensor by removing the sensor from the
housing and either blowing gas on the sensing surface or gently wiping the sensing surface with a damped
cloth.
Mounting of the Transmitter: The transmitter is approved for indoor as well as outdoor use.
However, avoid mounting in an area where direct sun might heat up the analyzer beyond the recommended
operating temperature range. If possible, install a small hood over the analyzer for rain water drain and to
prevent over-heating of analyzer.
Gas Connections:
The Inlet and outlet vent gas lines require 1/8” or ¼” stainless steel compression
type tube fittings. The sample inlet tubing must be metallic, preferably SS. The sample vent line may be of
SS or hard plastic tubing with low gas permeability.
Power Requirement: Supply power to the analyzer only as rated by the specification or markings on
the analyzer enclosure. The GPR-7500AIS is powered by 12-24 VDC or 100/230 VAC supply (check the QC
certificate to ensure the power requirement of your analyzer). The wiring that connects the analyzer to the
power source should be installed in accordance with recognized electrical standards. Ensure that the
analyzer case is properly grounded and meets the requirements for area classification where the analyzer is
installed. Never yank wiring to remove it from a terminal connection.
Power Consumption: The maximum power the analyzer consumes is no more than 7 Watts.