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Brand: Watson Smith
Watson Smith FRI-30 Indicating Air Flow Controller for Level Purge
Description
An adjustable air purge flow controller with a built-in flow indicator
The Watson Smith FRI-30 is an adjustable indicating air flow controller that combines a differential regulator, a needle valve and a variable area flow meter in one panel-mounted unit. The datasheet says it is suitable for level control and air purge applications, ideal for control room installation, and it carries a tamperproof cover and high accuracy. It is available for standard and hazardous applications.
In a bubbler-type level application a steady small flow of air or gas, sometimes nitrogen, is passed down a dip tube, and the pressure needed to push it out reflects the liquid head. The regulator holds a fixed 5 psi (0.3 bar) differential across the needle valve so the flow stays constant as the supply or back pressure varies, and the supply pressure at the inlet must exceed the maximum expected head pressure plus 5 psi so that flow can be maintained at maximum level. We found this datasheet only as a copy issued as Watson Smith Instrumentation literature (dated 10/06) and hosted by a UK instrument supplier; we did not find the product in current manufacturer literature, so treat it as an older, legacy line and confirm current availability, any replacement model and lead time before you rely on it.
Technical specifications
| Parameter | Specification |
|---|---|
| Function | Adjustable indicating air flow controller: differential regulator, needle valve, variable area flow meter |
| Part numbers | 250000R (0.2 to 2 scfh); 260000R (100 to 1000 cc/min) |
| Supply pressure | Up to 100 psi (7 bar, 700 kPa) |
| Fixed differential pressure | 5 psi (0.3 bar, 35 kPa) |
| Media | Air or dry non-corrosive gas filtered to 25 micron |
| Working temperature | 0 to 60 degrees C |
| Connections | Inlet 1/4 NPT; outlet 1/4 inch OD tube |
| Mounting / finish | Panel, upright; natural aluminium and black stove enamel |
| Weight | 600 g |
| Body material | Die-cast zinc alloy |
| Flowmeter tube / float | Acrylic tube; glass float |
| Diaphragm / internals | Fairprene diaphragm; stainless steel and brass valve and internal parts |
Ordering and what to confirm
Two ranges are listed: 250000R for 0.2 to 2 scfh and 260000R for 100 to 1000 cc per minute. Choose the range from the dip tube size and bubble rate you need. Confirm the supply pressure margin, the medium (air or dry non-corrosive gas filtered to 25 micron), the 1/4 inch OD tube outlet and 1/4 NPT inlet, the panel cut-out shown on the datasheet drawing and the availability of this older model. The datasheet says a version for hazardous applications exists, but it does not give approval details, so ask for them in writing if you need a certified unit.
Documents and quotation
The datasheet is attached for download. Seven Star LLC is an independent supplier in Muscat. Send the model or order code, quantity and operating conditions and we will request a quotation; availability depends on the model. Related items: Flow Indicators and Switches.
Datasheets & Documents
- Datasheet Watson Smith FRI-30 indicating air flow controller datasheet (10/06, controlled doc. 2006-128a) Download
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About brand
Watson Smith is a British maker of pneumatic instrumentation in Leeds, best known for its I/P converters that turn a 4-20 mA signal into a proportional air pressure for valve positioners and actuators. The business was started by John Watson and later joined by John Smith. It became part of IMI in the mid-1980s and is now Norgren's centre of excellence for instrumentation and positioning control.
Seven Star LLC is an independent supplier in Muscat. We list Watson Smith instruments for pneumatic control loops in Oman and the GCC.
Watson Smith company profile
| Origin | Leeds, England, founded by John Watson; John Smith joined in the 1950s |
|---|---|
| Site | Cross Chancellor Street, Leeds |
| Ownership | IMI, through Norgren, since the mid-1980s |
| Role in group | Norgren's centre of excellence for instrumentation and positioning control |
| Product families | Type 100X and 101X I/P converters, electronic, proportional and electro-mechanical I/P and E/P converters, Type 70 and Type 77 pneumatic transmitters, valve positioners |
Milestones
- 1950s: John Smith joins the business.
- Mid-1980s: IMI acquires Watson Smith.
Watson Smith product series
I/P converters include the 100X and 101X series, the Type 422 intrinsically safe converter with fail-freeze function and the Type 140 failsafe converter in explosion-proof and intrinsically safe versions; they turn a 4-20 mA signal into a pneumatic output for valve positioners and actuators. The Type 68 P/I transmitter and the Type 71 intrinsically safe P/I converter do the reverse, turning pneumatic pressure into 4-20 mA.
Manostat products include manually and mechanically operated precision pressure regulators and the SP2G2 remote manual and auto/manual loading stations. The Type 300D is a portable digital pressure meter and the FRI-30 an indicating air flow controller for level purge systems.
Where Watson Smith instruments are used
Pneumatic control valves and dampers driven from a DCS or PLC, bubbler level systems, instrument air regulation, test benches and older pneumatic loops in refineries, power stations and process plants.
Watson Smith products we list
Ordering Watson Smith instruments: what we need
Send the type and full code, input and output ranges, supply pressure, connection threads and hazardous-area certification. Each product page states the datasheet it is based on; where only an older datasheet exists, we ask you to confirm availability before ordering.
Facts checked against Norgren's company history and UK Companies House records, October 2026.
Browse Watson Smith products by category: Pressure Instrumentation, Regulators.
Related products
Frequently Asked Questions
What is the FRI-30 used for?
Level control and air purge applications, giving a constant, adjustable, indicated flow of air or gas, typically to a bubbler dip tube.
How does it keep the flow constant?
A differential regulator holds a fixed 5 psi drop across the needle valve.
What supply pressure is needed?
The inlet pressure must exceed the maximum expected head pressure plus 5 psi, with a maximum of 100 psi (7 bar).
Which flow ranges are offered?
0.2 to 2 scfh (250000R) or 100 to 1000 cc per minute (260000R).
Is it still current?
Only a 2006 datasheet was found, so confirm availability and any hazardous-area approval before ordering.
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