Omega PX838 User Manual

User’s Guide

PX838

High Media Compatibility

Wet/Wet Differential Sensor

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certification. The information contained in this document is believed to be correct, but
OMEGA Engineering, Inc. accepts no liability for any errors it contains, and reserves the
right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for,
patient-connected applications.

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Where Do I Find Everything I Need for

Process Measurement and Control?

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M-3296/0300

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
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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
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shall OMEGA be liable for consequential, incidental or special damages.

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“Basic Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or
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additionally, purchaser will indemnify OMEGA and hold OMEGA harmless from any liability or
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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 CUST OMER SERVICE DEP ARTMENT (IN ORDER TO A VOID
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:

1. Purchase Order number under which the
product was PURCHASED,

2. Model and serial number of the product under
warranty, and

3. Repair instructions and/or specific problems
relative to the product.

WARRANTY/DISCLAIMER

RETURN REQUESTS/INQUIRIES

FOR NON-WARRANTY REPAIRS, consult
OMEGA for current repair charges. Have the
following information available BEFORE contact­ing OMEGA:

1. Purchase Order number to cover the COST of
the repair,

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.

Installation

CA UTION:

1. INCORRECT ELECTRICAL CONNECTIONS CAN, IN CERTAIN CIRCUMSTANCES, DESTROY THE ELECTRONIC OUTPUT

CIRCUIT

.

2. BEFORE APPLYING ELECTRICAL POWER, MAKE SURE THE SUPPLY VOLTAGE IS TO THE CORRECT RATING.

3. THIS A VERY SENSITIVE SENSOR. ONLY APPLY PRESSURE WITHIN THE PRESSURE RANGE.
Mounting

Two M5 threaded holes in the base of the sensor provide mounting points.

Note: The screws must not enter the holes more than 0.472" into the sensor body.

The installed position of the sensor should be away from sudden temperature variations,
shocks and vibrations and should not be close to strong electromagnetic fields
(transformers, motors etc.). The sensor can be mounted in any position, but mounting at
an angle may require zero adjustment.

terminal
block

zero adjustment
(fine)

zero adjustment
(coarse)

cable gland

span adjustment

Internal detail

Electromagnetic Interference

To avoid electrical interference, use shielded cable with the shield connected to the earth
ground at both ends. The ground of the sensor can be the casing or the ground terminal
screw.

Electrical Connections
PX838 Series (current output)

The maximum allowable load resistance is calculated to
formula:

PX838 Series (Unidirectional voltage output)

Minimum load 2kW

Note: Connections 5 and 6 are common.

If the output cable passes through an area of electrical
disturbance, use a recommended load impedance of
between 2 kW and 10 kW. Connect the load resistance
between the wires corresponding to signal and - terminal at
a point furthest from the sensor; this produces a circulating
current.

R Max = 0.05 (V supply - 10) kW
Where: R Max in kW and V in V olts

PX838 Series bidirectional operation using
bipolar power supply (±1 2 Vdc) with bidirectional
output (0±5 Vdc or 0±2.5 Vdc)

Specification

Pressure range:..........................................................................................4 inH2O to ±150 psid

Pressure media:

Connect the power supply to + for positive,

- for negative, and 0 for neutral; connect the output
to signal for positive and 0 for negative signal.

Purging or de-gassing the sensor
Two 5 mm hexagonal socket bleed screws are located on the outer casing and can be

loosened to bleed the two pressure connections. Make sure that these screws are
tightened after this operation.

Note: It is possible to changeover the bleed screws and pressure connections enabling

easier access or for installation in a difficult position.

SIGNAL0

Adjustments

The following equipment is required to carry out the adjustments:

r Power supply

r Voltmeter or

r Milli-ammeter

r Pressure standard
u Connect the sensor as shown in Installation. The sensor should be put in its normal

operating position (vertical or horizontal). Remove the cover to gain access to the zero
and span adjustment potentiometers.

X750 diaphragm An y fluids, compatible with stainless steel (316L),
X750 Inconel, 600 Inconel and viton.

Beryllium copper diaphragm Any fluids, compatible with stainless steel (316L),
beryllium copper, brass and sof t solder and viton.

Accuracy:...............................................................................................................±0.25% FS BSL

(including linearity, h ysteresis and repeatability)

Long term stability:.....................................±0.3% over 1 year at stabilized temperature

Weight

(approximate)

...........................................................................................................3.3 lbs

Dimensions.......................................................................................................................see below

Power supply

......................................................................................................................................10 to 30 V d.c.

PX838 (0 to 10 V output)........................................................................................16 to 30 V d.c.

PX838 (0 to ±5 V output)................................................................................................±12 V d.c.

Low

High

0.68

0.26

G1/8 Female via
welded ad apter

Mounting:

2xM5 holes x 0.472 DP
on 2.66 centers

Pressure Ports:

Zero adjustment

u Zero adjustment is carried out with no pressure applied.
u Depending on the model, set the zero adjustment to: 0.00 V, 2.50 V, 4.00 mA or 12.0 0 mA

Span adjustment

u Span adjustment is carried out with the required span pressure applied to the +

pressure connector.

u Depending on the model, set the span adjustment to: 5.00 V, 10.00 V or 20.0 0 mA.
u Release the pressure.

Completion

Check the output at zero pressure and if necessary, repeat the zero and span adjustments.

r Release the pressure and disconnect the equipment.
r Refit the cover.

3.11

2.80

Pg7 Cable
Gland

Dimensions

Purge Ports:

High Pressu re
Low Pre ssure