Omega Products FMA-900-I Installation Manual

FMA-900 SERIES

Air Velocity Transducers

MADE IN

Standard

Remote Probe

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It is the policy of OMEGA Engineering, Inc. to comply with all worldwide safety and EMC/EMI
regulations that apply. OMEGA is constantly pursuing certification of its products to the European New
Approach Directives. OMEGA will add the CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct, but OMEGA 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, human applications.

General Description

The OMEGA®FMA-900 air velocity mass flow transducer is ideal for economical
monitoring of clean air flows in ducts and pipes, while producing very little
permanent pressure drop in the flowstream The FMA-900 employs two rugged
glass-coated RTD elements, protected by a

1

⁄4" diameter 304SS tube with a
“window” cut out. One RTD is the velocity sensor, while the other RTD provides
ambient air temperature compensation. The velocity sensor is heated to maintain
a constant (approximately 30°C) temperature differential above the ambient air
temperature, as measured by the second RTD element. The cooling effect of the
air flow experienced by the velocity sensor is measured and converted to an
electrical output signal proportional to air velocity. The FMA-900 is provided
with a 13" long probe as standard. The 304SS tubing is provided with inch marks
for ease of insertion depth.

Unpacking

Remove the Packing List and verify that you have received all equipment. If you
have any questions about the shipment, please call the OMEGA Customer
Service Department.

Upon receipt of shipment, inspect the container and equipment for any sign of
damage. Note any evidence of rough handling in transit. Immediately report any
damage to the shipping agent.

The carrier will not honor any claims unless all shipping material is
saved for their examination. After examining and removing contents,
save packing material in the event reshipment is necessary.

The following items are supplied with the FMA-900:

• FMA-900 Series Air Velocity Transducer

• Mating connector

• Removable plastic protective cover (supplied on the sensor tip)

• Operator’s manual

15-18 Vdc

INPUT

0-5 Vdc or 4-20 mA
OUTPUT

DUCT, PIPE
HOOD,
ETC.

FLOW

10 TO 10,000

FPM

COMPRESSION

FITTING

AIR VELOCITY SENSOR

TEMPERATURE SENSOR

FMA-900 Series Air Velocity Transducers

NOTE

1-1

Important Considerations Before Installation

The FMA-900 air velocity transducer is not explosion-proof, nor is it
intrinsically safe. Do not use for flammable or hazardous gases, or in
hazardous areas.

The FMA-900 air velocity transducer is intended for use with clean air or
nitrogen ONLY. Do not use with other gases, as other gases will produce an
uncalibrated, non-linear output signal. In addition, air carrying dust or oil (such
as found in blower/compressor systems that utilize oil) can lead to coating of the
sensor and thus, inaccurate readings. Refer to the Maintenance section for more
information on cleaning the sensor.

The FMA-900 is a bi-directional device; flow in the forward or reverse direction
provides the same output.

Installing the Flowmeter

The FMA-900 air velocity transducer can be mounted vertically or horizontally
without shift in calibration.

1. Remove the plastic protective cap from the sensor tip.

2. Run a length of straight pipe before and after the flowmeter. The amount of
upstream straight pipe run required depends upon the type of obstruction which
is immediately upstream of the flow sensor. See Table 2-1 for specific
requirements. Downstream of the flow sensor, in all situations, run 5 diameters
of straight pipe, regardless of the downstream obstruction.

3. Align the FMA-900 with the air flow. Make sure the width of the electronics box
(2 inches) is parallel with the flow stream.

The score line on the tubing is another way of aligning the air flow sensor with
the flow stream. The score line starts from the center of the transducer window
and as a result it can be aligned properly.

One means of installing the probe into a flow stream is to utilize a compression
fitting, such as OMEGA’s SSLK-14-14 stainless steel compression fitting with
Teflon ferrules, which permits adjustment of the insertion depth of the probe.

On Remote Probe Models (-R), connect the remote probe cable to the Electronic
Housing.

FMA-900 Series Air Velocity Transducers

CAUTION

!

1-2

Table 2-1 Piping Requirements

Recommended

Straight Pipe

Length "A"

Typical Piping Remarks

Without

Vanes

With

Vanes

15D 15D Closed Branch

A

A

A

A

A

A

A

A

20D 15D

Elbow. Tee,
Branch Pipe

25D 15D Elbow, 2 planes

25D 15D

Long-radius
bends

30D
25D

15D
15D

Elbow
Long-radius
bends

40D
35D

15D
15D

Elbow
Long-radius
bends

20D 15D Contracting Pipe

40D 20D Expanding Pipe

Recommend Meter

Be Installed

Upstream

Regulating,
reducing valves
Ball, check valves
Shut-off valves

Varied SectionValves Fittings in Two Planes All Fittings in Same Plane

Note: Straight pipe length on the downstram side to be 5 pipe diameters minimum.
* D – Pipe internal diameter.

A

A

FMA-900 Series Air Velocity Transducers

1-3

FMA-900 Series Air Velocity Transducers

Wiring the Flowmeter

1. Connect pins as follows:

PLUG PIN NO.

DESCRIPTION

1 0-5 Vdc or 4-20 mA Output (−)
2 0-5 Vdc or 4-20 mA Output (+)
3 Power Supply (+)
4 No Connection
5 No Connection
6 Power Supply (−)

2. Blow clean air through the FMA-900.

3. Install the sensor into the pipe or duct.

Measuring Air Flow

The FMA-900 measures standard velocity, which is the mass velocity of the air
referenced to 25°C and 760 mm Hg. No temperature or pressure corrections are
required. Where SCFM (standard cubic feet per minute) measurements are
desired:

1. Locate the point of average velocity in the pipe or duct.

2. In round pipes, under turbulent flow conditions (where the Reynolds number is
greater than 5,000), mount the velocity sensor approximately

1

⁄8 of a pipe
diameter in from the the pipe wall. For example, in an 8" diameter pipe, mount
the probe 1" in from the pipe wall.

3. For pipes or ducts where the flow is not turbulent, or the flow profile is not
symmetrical (due to inadequate straight pipe runs, etc.), perform a traverse of
the duct, in accordance with standard duct traversal methods as recommended
by ASHRAE or the National Air Balance Council.

4. To obtain SCFM, once the probe is mounted in the location of average velocity,
multiply the average velocity readings (in SFPM, standard feet per minute) by
the cross-sectional area of the pipe or duct, in square feet. For standard pipe,
these values can be found in the technical section of the OMEGA Complete
Flow and Level Measurement Handbook and Encyclopedia

®

.

Maintenance

Except for intermittent removal of the sensor from the line for cleaning, there is
no routine maintenance for the FMA-900. If the probe becomes coated with dust,
blow the dust away with clean air. If the probe is coated with sticky material,
clean it with a solvent which is compatible with epoxy, glass, and 304SS, and
which will not leave a residue on the sensor. You may clean the sensor with
water or alcohol (Ethanol) and an artist’s brush.

Calibration

Each FMA-900 is individually calibrated in a NIST-traceable wind tunnel. For
calibration certification or calibrating to a new range, the unit must be returned
to OMEGA. To obtain an Authorized Return (AR) number, call the OMEGA
Customer Service Department with a Purchase Order number to cover the
recalibration charges.

1-4

FMA-900 Series Air Velocity Transducers

Specifications

Ranges:

Model No. Model No.

0-5 V Output 4-20 mA Output Range

FMA-900-V FMA-900-I 0-100 SFPM
FMA-901-V FMA-901-I 0-200 SFPM
FMA-902-V FMA-902-I 0-500 SFPM
FMA-903-V FMA-903-I 0-1000 SFPM
FMA-904-V FMA-904-I 0-2000 SFPM
FMA-905-V FMA-905-I 0-5000 SFPM
FMA-906-V FMA-906-I 0-10,000 SFPM

Accuracy: ±1.5% of Full Scale at room temperature. Add ± 0.5% of reading

from 32 to 122°. Add 1% Full Scale below 1,000 SFPM.

Repeatability: ± 0.2% of Full Scale

Response Time: 400 milliseconds to within 63% of final value at room temperature

Probe: Aluminum oxide ceramic glass coating and epoxy;

probe body 304SS

Probe Temperature/ -40 to 250°F (-40 to 121°C); 150 PSIG maximum
Pressure:

Remote Probe (-R): Available with 15' (4.6 m) shielded cable between the Probe and

the Electronic Housing

Electronics Temperature
Range: Operating: 32 to 122°F (0 to 50°C)

Storage: 32 to 158°F (0 to 70°C)

Ambient Temperature
Compensation: About 5 minutes for 20°F ambient temperature change

Power: 15 to 18 Vdc at 300 mA

(15 to 24 Vdc at 300 mA for 0-100 SFPM and 0-200 SFPM ranges)

Output Load Resistance: Voltage: 250 ohms minimum

Current: 0-400 ohms maximum; 4-wire

Accessories: Mating connector prewired to 15 feet shielded cable with built-in

ferrite core included

Dimensions: Case: 3.5" H x 2" W x 1.25" D

(89 mm H x 51 mm W x 31.8 mm D)
Probe: 1/4" (6.35 mm) O.D., 13" long standard (330 mm),

3.75" long optional (“-S”)

Weight: 0.35 lbs. (0.16 kg)

1-5

FMA-900 Series Air Velocity Transducers

OTHER IMPORTANT CONSIDERATIONS BEFORE INSTALLATION

---------------------------------------------------------------- CAUTION----------------------------------------------------

Follow All Safety Precautions and Operating Instructions Outlined in this Manual.

The Unit May be Powered from a DC Power Supply. The Power Supply Should Have
Integral Impedence Protection.

Recommended Wiring Cable: Shielded 4-Conductor Cable, 22 or 24 AWG Stranded.

Recommended Power Supply Rating: 0-24 Vdc @ 300 mA, 7.2 VA

There are No User Replaceable Fuse in this Product.

Avoid Contact with Hazardous Live Parts.

Do Not Operate in Flammable or Explosive Environments.

This Product is for Use Only with Equipment which has no Accessible Live Parts.

------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------------

+

-

+

-

3
6
2
1

Red

Black

White

Output

(0/5 Vdc or 4/20 mA)

Green

Digital

Voltmeter/

Ammeter

DC

Power

Supply

FMA-900

7

Shield

TYPICAL INSTALLATION SCHEMATIC

1-6

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 in which wear is not warranted, include but are 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 the
company will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF
TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE 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 W

ARRANTY 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.

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 2006 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.

M1893/0305

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