Gas Blending; Operation With External Devices; Operation With A Hastings Power Supply - Teledyne HASTINGS Everywhereyoulook 200 Series Instruction Manual

201/203/205/207 Series Flowmeters and Controllers Instruction Manual
2.6.4.

Gas Blending

In the blending of two gases, it is possible to maintain a fixed ratio of one gas to another. In this case,
the output of one flow controller is used as the setpoint or a scaled setpoint signal of a second flow
controller. The output signal of the first flow controller controls the flow rate of the second gas as a
percentage of the flow rate of the first gas. Multichannel Hastings Power Supplies allow users to
configure this option (see Ratio Control), but other devices can be used to achieve this affect provided
they can scale the output signal of one controller and feed it to the input of the other.
The following formulas are useful:
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In most cases the analog output full scales are the same so those two terms cancel out.
EXAMPLE: Controller A is a 5 V controller with a full scale flow rate of 100 SLM. Controller B is a 5 V
controller with a full scale flow rate of 10 SLM. What gain factor on the output of controller A will result
in controller B flowing 5% of controller A?
Use the formulas above:
Cut the output of controller A in half and route the signal to the setpoint of controller B to flow 5% of
controller A.

Operation with External Devices

2.7.1.

Operation with a Hastings Power Supply

Hastings power supplies display flow instrument outputs (in flow units or percent of full scale) and offer
users an easy setup for controlling and monitoring each instrument's status. Meters connected to
Hastings power supplies simply have their output signals displayed on the front screen. Controllers have
three states of operation when connected to a Hastings power supply: AUTO, OPEN, and CLOSED. Buttons
on the supply front panel allow users to toggle between these states. Controllers in the "AUTO" state
will accept setpoint commands from a Hastings power supply and control the flow rate accordingly. The
valve changes its position with the user input setpoint, and the setpoint issued to a controller can be
adjusted using the other available buttons on the supply front panel. Controllers in the CLOSED state
have their valves overridden shut and will not accept setpoint commands. The OPEN state overrides the
valve fully open regardless of any user setpoint. The OPEN position is useful for purging systems. See the
following power supply feature guide.
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