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Low Flow Indicating Paddlewheel Flow Meter

Micro-flow meter


Item# FTB321D

Volume discounts available
Volume Discount Schedule
Quantity Price each
1-4 $362.85
5-9 $344.71
10-24 $337.45
25-49 $322.94
50-99 $315.68
100+ $308.42

In stock

Lead Time ( If not in Stock): 3 weeks

Micro-flow meter FTB321D FTB321D
  • NEMA 4X (IP56) Enclosure
  • 6-Digit LCD
  • Displays both Rate and Total
  • Non-Volatile Programming and Total
  • For Clean Liquids

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Flow Range
Max Process Temperature
Max Operating Pressure
Wetted Materials
Output Signal
Supply Power
Process Connection Type
Process Connection Size

Product Specs

The FTB300 Series of digital paddle wheels are an economical choice for low flow rate applications. They use Infra-red light beam technology. Available connections include 1/8 FNPT, 1/4 FNPT and 3/8" OD tube fittings. Six available flow ranges as low as 30ml/min to 7000 ml/min. No display models have a 5 Vdc current sinking pulse output. Units with displays have a 6-digit LCD, with up to 4 decimal positions that display both flow rate and total. All units include an open collector alarm output.

User selectable scale factors include: flow units, gallons, liters, ounces, and milliliters. Time units include: minutes, hours, days. Users can also program custom units. Programming values and total are stored in the non-volitile memory. The total reset function can also be disabled. Standard units have a clear PVC viewing lens, PVDF chemical resistant lens are available as an option. The enclosure is a weather resistant Valox PBT and rated NEMA 4X (IP56).

Max Working Pressure:
    PVC Lens: 9 bar (130 psig) at 21°C (70°F)
    PVDF Lens ("-PVDF" Option): 150 psig (10 bar) @ 21°C (70°F)
Max Fluid Temperature:
    PVC Lens, FNPT Connectors: 54°C (130°F) at 0 PSI
    PVDF Lens ("-PVDF" Option), Tubing Connectors: 93°C (200°F) at 0 PSI
Full Scale Accuracy: ±6%
Input Power Requirement: 9 to 28 Vdc
Sensor Type: Infrared light beam
Alarm Output: Open collector 30 Vdc max
Enclosure: NEMA 4X (IP56)
Approximate Shipping Wt: 0.45 kg (1 lb) Materials of Construction
Body, Paddle, Axle Material: PVDF Connector Material
FNPT Connections: PVC
Tubing Connectors: PVDF Viewing Lens Material Option
    Clear See Through: PVC
    Opaque Chemical Resistant: PVDF (optional)
O-Ring Seals: FKM (EPDM optional)
Compression Seal to Pump: PVC Sensor Only
    Models: 5 Vdc digital square wave (2-wire)
    Output: 3-wire shielded cable, 1.8 m (6')

Model with Display Model without Display Range
1/8 FNPT 1/4 FNPT 3/8" OD Tube 1/8 FNPT 1/4 FNPT 3/8" OD Tube lpm gph
FTB311D FTB321D FTB331D FTB311 FTB321 FTB331 0.03 to 0.3 0.48 to 4.7
FTB312D FTB322D FTB332D FTB312 FTB322 FTB332 0.1 to 1 1.6 to 15.8
FTB313D FTB323D FTB333D FTB313 FTB323 FTB333 0.2 to 2 3.2 to 31.7
FTB314D FTB324D FTB334D FTB314 FTB324 FTB334 0.3 to 3 4.8 to 48
FTB315D FTB325D FTB335D FTB315 FTB325 FTB335 0.5 to 5 7.9 to 79
FTB316D FTB326D FTB336D FTB316 FTB326 FTB336 0.7 to 7 11.1 to 111

Rated 5 out of 5 by from Great little flow meter We purchased this flow meter for a test project and we really loved the ease of use and accuracy. Would definitely recommend this product to others.
Date published: 2015-11-24
Rated 5 out of 5 by from Right Tool for the Job. Bought this, received fast, fairly priced, and the perfect tool for my needs.
Date published: 2016-04-29
Rated 4 out of 5 by from Great product Good and precise flow meter, in addition, should have a hard reset switch, in case of the error
Date published: 2016-10-10
Rated 1 out of 5 by from Fittings don't fit The fittings that came with the flow meter did not actually fit. And they only sent one. We have been in contact with Omega for several weeks now trying to fix the issue and it has not been resolved.
Date published: 2021-03-11
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What are the dimensions of the FTB311 Micro-Meter

Asked by: EngieTechie
Thank you for your question. A file has been sent to your email with dimensions for this part..
Answered by: application engineer je
Date published: 2019-07-01

Do you have a larger unit that can measure ~ 1-10 gal/min?

Asked by: MolecularExpress
Thank you for your inquiry about a flow meter. Please compose an email and send to flow@omega.com and can provide options that best fits your application.
Answered by: JC ENGR
Date published: 2020-07-25

What are the dimesions of this meter?

Asked by: Ozzie
Please contact the Flow engineering department with this request and they will send you the details. Please send to flow@omega.com
Answered by: AS Engineer
Date published: 2019-10-18

When this meter totals the volume does it account for reverse flow by subtracting from the volume total so that a tank level can be estimated from flow in and out?

Asked by: Engineer13
No matter which direction the paddlewheel spins the meter will accumulate a positive total.
Answered by: ASE HPO
Date published: 2019-12-19

What are the dimensions for this part, with and without the LCD screen?

Asked by: LGooge
Thank you for your inquiry. It would be best to compose an email and forward to flow@omega.com and will have our design team provide the information for this microflow meter.
Answered by: Applications Engineer JC
Date published: 2020-02-19

The flowmeter stopped working after 4 months installed in a pressure manifold. The sensor had continuous power during the time, the failure was found on the infrared sensor once the flowmeter was replaced. What is the life expectancy of the sensor?

Asked by: Rvasques
Thanks for your question. The life expectancy of the flow meter depends on the each individual application. Customers have this flow meter after 3 years and still working while others fail after 4 months. Send us an email or call us with more details of your application.
Answered by: ASE HPO
Date published: 2019-11-09

Why is there a difference of total volume between the data calculated from the Lab view and the reading on the screen?

Asked by: dfse
Thank you for your inquiry. Please e-mail flow@omega.com and our Flow Engineers can help you with this concern.
Answered by: AS Engineer
Date published: 2021-01-08

Is there an wiring schematic for the flow meter itself, instead of just the strainer that's in the manual? I'd like to output the signal to another unit if that's possible.

Asked by: alexjlove
We can send a copy of the wire schematic for this flow meter, please send that request to flow@omega.com which would be much appreciated. Thank you.
Answered by: Applications Engineer JC
Date published: 2019-11-16
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