User’s Guide
TM
omega.com
®
e-mail: [email protected]
PX791 & PX792 Series
Sanitary Pressure Transducer
PX791 & PX792 SERIES
OMEGA® SANITARY PRESSURETRANSDUCER
INSTRUCTION SHEET
W A R N I N G !
This instrument is susceptible to damage when exposed to static
electrical charges. To avoid damage to the transducer observe the
following:
• Ground the body of the transducer BEFORE making any electrical
connections
• When disconnecting, remove the ground LAST.
NOTE: The braided shield and drain wire in the cable (if supplied) is not
connected to the transducer body, and is not a suitable ground.
CAUTION: Pressure spikes in excess of the rated overpressure capabil-
ity of the transducer may cause irreversible electrical and/or mechani-
cal damage to the pressure measuring and containing element(s).
Excitation (Ratiometric Output Only)
Mounting
For proper operation a voltage within the range
of 5 to 10 Vdc must be applied between the
transducer’s supply terminals.
Although the unit can withstand normal vibra-
tion without damage or significant output
effects, it is always good practice to mount the
transducer where there is minimum vibration. Be
sure to use a gasket that does not interfere with
the sanitary diaphragm. If the gasket I.D. is
smaller than 1.50 inches, an offset due to
clamping force will occur.
Noise
For minimum noise susceptibility, avoid running
the transducer’s cable in a conduit that contains
high current AC power cables. Where possible
avoid running the cable near inductive equipment.
Power Supply
The supply voltage for the 1-5 and
Shield Wiring
Connect the braided shield to the guard terminal
on the reading instrument (meter, etc.) if avail-
able or to ground or to the power supply nega-
tive terminal.
1-6 Vdc output transducers must be within the
range of 10 to 36 Vdc. The maximum supply
voltage for a 4-20mA current output transducer
is 36 Vdc while the minimum supply voltage is
dependent upon the loop resistance of the circuit.
Refer to Figure 1. The loop supply voltage vs.
loop resistance shows the minimum supply
voltage (Vmin) required for a given loop resistance
(RLOOP).
Adjustment Potentiometers
The zero and span pots are accessible through
the top of the case. Loosen the four screws and
separate the top carefully. The zero pot is marked
with a white dot.
PX791 & PX792 Series
Vent Tube
The cable will have a clear Teflon vent tube that's
required at pressure below 500 psi to provide
atmospheric reference. The open end should be
placed in a dry area.
Dimensions
A
Life Support Policy
These products are not authorized for use as
critical components in life support devices or
systems. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical
implant into the body, or (b) support or sustain
life, and whose failure to perform, when prop-
erly used in accordance with instructions for
use provided in the labeling, can be reasonably
expected to result in a significant injury
to the user.
B
2. A critical component is any component of a life
support device or system whose failure to per-
form can be reasonably expected to cause the
failure of the life support device or system, or
to affect its safety or effectiveness.
C
D
Figure 1. Loop Supply Voltage vs. Loop Resistance
MODEL
S15
A
B
C
D
SERIES
PX791
PX792
0.8
0.8
4.7
4.7
0.9
0.9
2.0
2.5
Loop Supply Voltage vs.
Loop Resistance
for 4-20mA Output Only
S20
1182
1000
750
500
250
0
0
10
20
30 36
Loop Supply Voltage (Vdc)
Vmin = 10V + [.022A*(RL)]
*includes a 10% safety factor
RL = RS + RW
RL = Loop Resistance (ohms)
RS = Sense Resistance (ohms)
RW = Wire Resistance (ohms)
PX791 & PX792 SANITARY TRANSDUCERS –
ELECTRICAL CONNECTIONS
Voltage Output Units 1-5, 1-6 Vdc
WARNING:
READ BEFORE
INSTALLATION
CABLE TYPE F2
Red
=
=
=
+Power
Common
Output
White
Green
The diaphragm is very sensitive and fragile!
Do not let anything touch the diaphragm but
the fluid to be measured. Fluid hammer and
surges can destroy any pressure transducer
and must always be avoided. A pressure
snubber should be installed to eliminate the
damaging hammer effects. Fluid hammer
occurs when a liquid flow is suddenly
stopped, as with quick-closing solenoid
valves. Surges occur when flow is suddenly
begun, as when a pump is turned on at full
power or a valve is quickly opened.
CABLE TYPE C1
Red
=
=
=
+
Power
White
Green
Common
Output
HIRSCHMANN TYPE
PIN-1
PIN-2
PIN-4
=
=
=
+Power
Common
Output
BENDIX 4-PIN, 6-PIN
Pin A
Pin B
Pin D
=
=
=
+Power
Output
Common
Current Output Units 4-20mA
Liquid surges are particularly damaging to
pressure transducers if the pipe is originally
empty. To avoid damaging surges, fluid lines
should remain full (if possible), pumps
should be brought up to power slowly, and
valves opened slowly. To avoid damage
from both fluid hammer and surges, a surge
chamber should be installed.
CABLE TYPE F2
Red
=
=
+Power
Power
Black
CABLE TYPE C1
Red
=
=
+Power
Power
Black
HIRSCHMANN TYPE
Pin-1
Pin-2
=
=
+Power
Power
Symptoms of fluid hammer and surge's
damaging effects:
a) Pressure transducer exhibits an output
at zero pressure (large zero offset). If
zero offset is less than 10% FS, user
can usually re-zero transducer, install
proper snubber and continue
BENDIX 4-PIN, 6-PIN
Pin A
Pin B
=
=
+Power
Power
Ratiometric (mV/V)
CABLE TYPE F2
monitoring pressures.
Red
=
=
=
=
+Power
– Power
+Output
– Output
White
Green
Black
b) Pressure transducer output remains
constant regardless of pressure.
CABLE TYPE C1
c) In severe cases, there will be no
output.
Red
=
=
=
=
+Power
– Power
+Output
– Output
White
Green
Black
HIRSCHMANN TYPE
Pin A
Pin B
Pin C
Pin D
=
=
=
=
+Power
+Output
– Output
– Power
BENDIX 4-PIN, 6-PIN
Pin A
Pin B
Pin C
Pin D
Pin E
Pin F
=
=
=
=
=
=
+Power
– Power
+Output
– Output
Shunt Cal.
Shunt Cal.
WIRING DIAGRAMS FOR ALLTRANSDUCERS
+
RED
(+ Power)
POWER
SUPPLY
WHITE (- Power)
–
TRANSDUCER
(+ Output)
(- Output)
GREEN
BLACK
+
–
METER
4-Wire Ratiometric (mV/V)
+
–
(+ Power)
POWER
SUPPLY
(Common)
TRANSDUCER
–
+
(+ Output)
METER
3-WireVoltage
POWER
SUPPLY
+
–
(+)
POWER
TRANSDUCER
OUTPUT
(–)
+
–
METER
4-20mA
WARRANTY/DISCLAIMER
OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a
period of 13 months from date of purchase. OMEGA’s Warranty adds an additional one (1) month grace
period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA’s customers receive maximum coverage on each product.
If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service
Department will issue an Authorized Return (AR) number immediately upon phone or written request.
Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no
charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser,
including but not limited to mishandling, improper interfacing, operation outside of design limits,
improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of
having been tampered with or shows evidence of having been damaged as a result of excessive corrosion;
or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating
conditions outside of OMEGA’s control. Components which wear are not warranted, including but not
limited to contact points, fuses, and triacs.
OMEGA is pleased to offer suggestions on the use of its various products. However, OMEGA
neither assumes responsibility for any omissions or errors nor assumes liability for any damages
that result from the use of its products in accordance with information provided by OMEGA, either
verbal or written. OMEGA warrants only that the parts manufactured by it will be as specified and
free of defects. OMEGA MAKES NO OTHER WARRANTIES OR REPRESENTATIONS OF ANY KIND
WHATSOEVER, EXPRESS OR IMPLIED, EXCEPT THAT OF TITLE, AND ALL IMPLIED WARRANTIES
INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PUR-
POSE ARE HEREBY DISCLAIMED. LIMITATION OF LIABILITY: The remedies of purchaser set forth
herein are exclusive, and the total liability of OMEGA with respect to this order, whether based on
contract, warranty, negligence, indemnification, strict liability or otherwise, shall not exceed the
purchase price of the component upon which liability is based. In no event shall OMEGA be liable
for consequential, incidental or special damages.
CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic
Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical
applications or used on humans. Should any Product(s) be used in or with any nuclear installation or
activity, medical application, used on humans, or misused in any way, OMEGA assumes no responsibility
as set forth in our basic WARRANTY/DISCLAIMER language, and, additionally, purchaser will indemnify
OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the
Product(s) in such a manner.
RETURN REQUESTS / INQUIRIES
Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE
RETURNING ANY PRODUCT(S)TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN (AR)
NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID PROCESSING
DELAYS).The assigned AR number should then be marked on the outside of the return package and on
any correspondence.
The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.
FOR WARRANTY RETURNS, please have the
following information available BEFORE
contacting OMEGA:
FOR NON-WARRANTY REPAIRS, consult OMEGA
for current repair charges. Have the following
information available BEFORE contacting OMEGA:
1. Purchase Order number under which the product
was PURCHASED,
1. Purchase Order number to cover the COST
of the repair,
2. Model and serial number of the product under
warranty, and
3. Repair instructions and/or specific problems
relative to the product.
2. Model and serial number of the product, and
3. Repair instructions and/or specific problems
relative to the product.
OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords
our customers the latest in technology and engineering.
OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 1999 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,
reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without the
prior written consent of OMEGA ENGINEERING, INC.
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