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200/202 Series Flowmeters and Controllers Instruction Manual
Output Signal
The standard output of the flow meter is a 0-5 VDC signal proportional to the flow rate. In Hastings power
supplies, the output is routed to the display and is also available at the terminals on the rear panel. If a
Hastings supply is not used, the output is available on pin 6 of the DA-15 connector (pin 2 of the DE-9 for 24
Volt) and is referenced to pin 5 (pin 8 for 24 Volt). It is recommended that the load
resistance be no less than 2kΩ. If the optional 4-20 mA output is used, the load impedance must be
selected in accordance with Section 1.4.
Mechanical Connections
2.4.1.
Mounting
If the instrument uses a dense gas or high pressures, the instrument must be installed horizontally.
Outside of this special case, the flowmeter may be mounted in any position provided the direction of
gas flow through the instrument follows the arrow marked on the bottom of the flowmeter case label.
Having the inlet and outlet fittings in a horizontal plane is preferred. Whenever a flow instrument is
mounted in a different orientation, the instrument should be re-zeroed at zero flow with the system
pressurized to the expected operating pressure.
NOTICE: The flow instrument should be installed in a clean and careful manner. Take care not to
drop the product and avoid impacts to prevent damage.
2.4.2.
Gas Quality
Impurities or foreign debris in the gas lines can have negative effects on device performance. The
smallest of the internal passageways in the HFM-200/HFC-202 Series is the diameter of the sensor tube,
0.0125" (0.31 mm), so the instrument requires adequate filtering of the gas supply to prevent blockage
or clogging of the tube.
2.4.3.
Upstream & Differential Pressure
The pressure regulator and the plumbing upstream must be of sufficient size to minimize changes in the
upstream pressure. In general, high capacity regulators and large internal diameter plumbing help to
make the system more stable. When switching from full flow to zero flow, the inlet pressure of the
instrument should rise to no more than 30% above the inlet pressure at full flow. The pressure drop
between the upstream regulator and the instrument should be minimized (use shorter length or larger
inner diameter pipe or tubing). The differential pressure across a meter should be less than 6" of H2O
(~0.217 psi) at maximum flow. Controllers may have much higher differential pressures depending upon
the size of the installed orifice.
WARNING: Make sure the work area is safe (de-pressurized) before installing a flow instrument. Make sure
emergency shutoff or pressure release valves are available for safe working conditions. Do not exceed 500
psig unless the flowmeter is specifically rated for higher pressures
2.4.4.
Other Mounting & Fitting Options, Notes
There are two 8-32 threaded holes, located on the bottom of the base that can be used to secure it to a
mounting bracket (screws provided). Other holes for special mounting can be added to the
endcap upon request. The standard inlet and outlet fittings for the 200/202 are 0.25" and 0.125"
Swagelok (optional VCR or VCO fittings). The O-rings for the end cap and the sensor are Viton® (optional
Kalrez® or Neoprene). It is recommended that all connections be checked for leaks after installation. Do
this by pressurizing the instrument (do not exceed 500 psig unless the Flowmeter is specifically rated for
EAR99 Technology Subject to Restrictions Contained on the Cover Page
Page 12 of 27
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