Omega FTB500 User Manual

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TABLE OF CONTENTS

FTB500 SERIES FLOWMETERS
SECTION
SECTION 1

1.1
I.2
I.3

1.3.1

1.3.2

1.3.3 Viscosity Calibration and UVC Curves

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . .

Description
Available Models
Theory of Operation
Performance Characteristics
Viscosity Effects

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PAGE

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SECTION 2 INSTALLATION

2.1

2.2

2.3

2.4

2.5

Unpacking
Operation

General
Installation Wiring Layout for Interconnections
Installation of the FTB500 Mini Flow Signal Conditioner

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..................................

.................................. .

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SECTION 3 CALIBRATION

3.1

3.2

3.3

3.4

3.4.1

3.4.2

Introduction
Calibration Procedure
To Confirm
Calibration of FTB500 Analog Output
Setup
Equations

.......................

.................

FTBSOO

Signal Conditioner Offset

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SECTION 4 MAINTENANCE

4.1

4.2

Introduction
Servicing and Preventative Maintenance of the
Flowmeter (Ball Bearing Design)

,

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.. .

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FTBSOO

. . . . . . . . . . .

SECTION 5 TROUBLESHOOTING AND MAINTENANCE
SECTION 6 RECOMMENDED SPARE PARTS LIST
SECTION 7 ACCESSORIES

SECTION 8 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . .

.6

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6
7
7

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8

.9

.I2

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I2

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12
I3

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I3

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13
I3

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.I5

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15
I5

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.20

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.20

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.21

SECTION 1 INTRODUCTION

1.1

DESCRIPTION

OMEGA@

The
low flow measurement of liquids and gases. They utilize a
rotor whose motion is converted into a pulse output proportional to flow
by a pickup coil. They come with an integral signal conditioner, powered

by either 15-35 VDC or 115 VAC (optional) to provide amplified frequency
and analog output. The signal conditioner corrects for the inherent zero off-
set of the flowmeter pulse output. It is mounted in a NEMA 4X, explosion

proof enclosure

II, groups E, F and G.

Features of the FTB500 include:

1.

Integral signal conditioner which provides K-factor offset correction for

the mini-flowmeters.

2. Versatile AC and DC power versions are available.

3. Configurable pulse voltage or analog output options.

FTB500 Series Low Flowmeters offer extremely accurate

(Adalet

XJS DO) rated for class I, groups C and D, and class

pelton

wheel-like

1.2

AVAILABLE MODELS

DESCRIPTION
(LINEAR FLOW RANGE)

STANDARD PART NUMBERS

0.02

to

0.15 GPM

0.025

to

0.25 GPM

0.05

to

0.5 GPM

0.1

to

1.0 GPM

0.2

to

2.0 GPM

OPTIONAL PART NUMBERS

TTL

Pulse output

0-5VDC

output

115VAC

signal conditioner power supply

PSIG

5000

(“CK)

*

Replace

tistokesl

X

1 for 501, 2 for 502, 3 for

in part number with the viscosity (in

of your liquid. The maximum is 25CK.

NOTE

503,4

PART NUMBER*

FTB501-(
FTB502-(
FTB503-(

FTB505-(“CK)

FTB50_X-(*CK)-P
FTB50_X-t”CKb5VDC
FTB5O_X-(*CK)-115VAC
FTB50_X-t*CK)-5KP

“CK)

“CK)
“CK)
‘CK)FTB504-(

for 504, or 5 for 505.

cen-

1

1.3

THEORY OF OPERATION

A simplified block diagram of the FTB500 Mini Flow Signal Conditioner is
shown in Figure 1-I.

SENSITIVITY

TURBINE FLOWMETER=

MAIN CHASSIS

Figure l-l.

FREQ. TO

CONVERTER

- -

Block Diagram

+v

FTBBOO

SIGNAL

CONDITIONER

CAPACITOR COUPLED

OUTPUT

pcA_,,B

ANALOG
OUTPUT

AMP.

The basic operation of the system is as follows:
The frequency signal from the flowmeter is connected to the FTB500 with

a twisted pair shielded cable. The signal enters through the SENSITIVITY
control which is used to reject unwanted noise by raising the trigger
threshold above the background noise present.

The low level flowmeter signal is then passed through a special condition-
ing chain where it is filtered, amplified, and shaped into a train of digital

pulses whose frequency is non-linearly related to the volume flow rate.
The digital pulse train is then passed through the linearizer where the off-

set frequency signal is injected into it. For flow rates within the range of the
meter, the linearizer output will be linearly related to the volumetric flow rate
In addition, this circuitry drives the ‘low flow ’ out of range indicator.

2

The signal entering the frequency to analog converter is passed through a
combination of divide by N and DIP switch matrix. The output is chosen
whose pulse rate is between 75 and 150 Hz at the maximum flow rate to
be measured. This scaled pulse rate is fed into a precision monostable cir-
cuit. The output of the monostable is then filtered into an analog voltage
that is proportional to flow.

The output amplifier will take this voltage and perform either a voltage to

voltage amplifier or voltage to current amplifier.

Finally, the output is divided by 8 to reduce irregular pulse spacing. Then,
the pulse train enters a buffer and an attenuator simultaneously. The buf-

fer output produces a square wave pulse which can be used as a

CMOS/lTL
compatible output. The attenuator produces a capacitor coupled AC out-
put which is suitable for driving other signal conditioners, indicators, or con-

trollers which require an AC signal input.

The output frequency from the FTB500 Series Turbine Meter versus flow

flowrate

is essentially a straight line of frequency as a function of

which
does not pass through zero. left uncorrected, this will result in a K-factor
which varies with flow rate.

The

FTBSOO

integral signal conditioner will compensate for the frequen-
cy offset characteristics of the flowmeter, by using the method of offset
frequency injection. Offset frequency injection is implemented electronically
by adding a signal equal to the offset frequency required to linearize the out-
put of the flowmeter. This effectively shifts the output characteristic to that
of the desired ideal. A low-flow cutout feature is provided where the off-
set signal is inhibited during no flow to prevent false outputs from being
generated.

The FTB500 Series Turbine Meter is a family of low flow rate measurement

pelton

devices based on a
tangentially through a velocity nozzle against the

wheel-like rotor. The measured fluid is directed

pelton

rotor causing it to
rotate The motion of the rotor is sensed by the pickup coil and converted
to a pulsing output signal where the frequency is related to the flowrate, and
the accumulated pulses are related to the total volume passing through the
flowmeter.

1.3.1

Performance Characteristics

FTBSOO

The basic performance characteristics of the

FTB500

in Figures l-2 and 1-3. The

Series of meters establish a linear

flowmeter are shown

response after an initial offset correction when operating at a constant
viscosity.

3

lL

/

UN LINEARIZED OUTPUT

FLOW RATE

(GPM)

Figure 1-2.

8
5

90

!

.80

7
f

1.00

u

Figure 1-3.

FTBSOO

Output Characterlstlcs Diagram

LINEARIZED

UNLINEARIZED

I_7

10 50 100

%

OF MAX IMUM

Normalized

FTBIOO

FLOWRATE

Calibration Curve

4

Over the linear flow range, the input/output characteristics takes the form of:
Equation 1
Frequency = C, x Flowrate-C,

FTB500

The
ditioner available in all OMEGA instrumentation. Accuracies of

Series Turbine Meter requires the use of a linearization con-

*l%

of

reading are typical after initial correction for offset. Better accuracies ap-

*2%

proaching
entire characteristics of the

are possible using smart transmitters which can store the

FTB500

Series Turbine Meter.

The K-Factor is the number of pulses per unit volume produced by the
flowmeter under a given set of conditions. Repeatability is a measure of the
stability of the output under a given set of flowing conditions. The
repeatability is defined as the allowable percentage deviation from the
stated K-Factor.

The pressure drop characteristics are given based on water at a viscosity
of 1 Cpse and a specific gravity of 1.00. For other fluid ’s, the following equa-
tion may be used to estimate the pressure drop across the
Turbine Meter given the pressure drop on water at the maximum

FTB500 Series

flowrate

and the fluids viscosity and density.
PSID

=

where:

(Cpsel”

(SpGr)”

x

Cpse is viscosity in centipoise
SpGr

is the specific gravity

H,O

PSID

is the pressure drop from Figure l-4

x

PSID

H,O

Figure 14.

Gross Pressure Drop Characteristic Curve on Water

5

1.3.2 Viscosity Effects

An ideal flowmeter may be defined as one in which the output is solely a
function of the fluid flow being measured. Real flowmeters display
dependencies on secondary fluid properties, such as viscosity temperature,
and/or pressure. These effects tend to obscure or degrade the precision of
the flow measurement.

In very few flowmeter designs, the viscosity dependency is well understood
and given suitable documentation, may be compensated for. The OMEGA
instruments are among this select group.

In selecting an
it is generally preferable to size the flowmeter so it will be operating in the
higher portion of its range to minimize viscosity effects in the measurement.
Some loss in flow turndown range may be expected.

FTB500

Series Flowmeter for operation on a viscous fluid,

1.3.3

Viscosity Calibration and UVC Curves
In some flowmeter applications the viscosity is held nearly constant owing

to regulated conditions of temperature and fluid consistency. For such ap-
plications it is only necessary to document the flowmeter ’s performance
at the expected operating viscosity. For such fixed viscosity applications
the standard specifications usually apply.

The

FTB500

Series Turbine Meter may be used over wide viscosity ranges,

since the flowmeter has a unique, documented, Universal Viscosity Curve

(abbreviated UVC) which is accurate to

In some applications, the fluid viscosity is a known function of temperature
A PC could be used to eliminate the otherwise adverse viscosity effect on
the flow measurement.

SECTION 2 INSTALLATION

2.1

UNPACKING
Remove the Packing list and verify that all equipment has been received.

If there are any questions about the shipment, please call the OMEGA
Customer Service.

Upon receipt of shipment, inspect the container and equipment for any
signs of damage. Take particular note of 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 con-
tents, save packing material and carton in the event reshipment

is necessary.

NOTE

*l%

of reading.