Celerity UNIT 1661 User Manual

3
3.3
Connector Options
The electrical connector configurations are shown in Appendice 16.1, “Electrical
Connections”. This includes detailed infor
mation and pinouts.
3.4 Special Adapters
Retrofitting of the models of most competitors is accomplished using special electronic and
mechanical adapters. Contact Celerity’s Applications Engineering department for help with
your particular requirement.
3.5 Valve Options
The valve is configured at the time of manufacture to be Normally Closed or Normally Open,
and is not user modifiable.
- Normally-closed (standard): The valve is closed when there is no power applied to the unit.
- Normally-open (optional): The valve is fully open when there is no power applied to the
unit.
3.6 Flow Direction Options
There are two configurations of Flow Direction, and this is not user modifiable.
- “Standard”:
- The sensor is upstream and the valve is downstream.
- The valve buffers the sensor from downstream (process) pressure fluctuations.
- “Pressure buffered”:
- The valve is upstream and the sensor is downstream.
- The valve buffers the sensor from upstream pressure fluctuations.
3.7 Auto-Zero Option
- The Auto-Zero feature detects zero offset during no-flow conditions and electronically
re-zeros the output signal.
- Auto-Zer
o, on earlier Unit models, was of great benefit in reducing drift and increasing
equipment uptime.
- However, the current sensor models have a drift specification of less than .6% per year.
- The proper application of the Auto-Zero option depends entirely on the ability to ensure
absolutely no fl
ow acr
oss the MFC sensor during the Auto-Zer
o cycle.
- With few exceptions, this means that there must be positive shutoff valves immediately
upstr
eam and downstr
eam of the MFC, and that ther
e must be pr
oper valve sequencing.
- All Digital Mass Flow Controllers have Auto-Zero circuitry installed, which can be enabled or
disabled using the MultiFlo V
ir
tual Inter
face. (Refer to the MultiFlo V
ir
tual Inter
face User’s
Manual.)
- For a more complete explanation of the the Auto-Zero Feature see Appendice 16.7.
- If you have any questions regarding the ordering or installing of an MFC with the Auto-Zero
feature please consult Applications Engineering first.
©2005 Celerity
, Inc.
#199-001-0006 REV
.F 4/05
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Celerity UNIT 1661 Specifications

General

Brand	Celerity
Model	UNIT 1661
Category	Measuring Instruments
Language	English