Barton Model 274A, 335A, 335P, 335T and 338E are pneumatic instruments. The consists of the product line of Pneumatic Transmitters and Indicating or Recording Controllers. All Barton 274A, 335A, 335P, 335T and 338E models are designed to meet the most stringent and demanding requirements for Oil & Gas Production, U.S. Navy Shipboard, and Process Plant applications.
The heart of the DP-driven instruments is the rugged Barton Differential Pressure Unit (DPU) – featuring a time-proven liquid-filled bellows and torque tube design. Recording
and Controlling models are also available with Pressure or Temperature actuators.
Pneumatic Transmitters (Standard DP and Linear-with-Flow)
• Barton Models 274A – DP Transmitters
• Actuated by Barton’s M199
• Rugged, Weatherproof, Non-corrosive Case
• Continuous Purging (pilot valve and nozzle exhaust inside)
• Operation Span Continuously Adjustable (100 – 20%)
• Adjustable Suppression (up to 80% of range)
• Large Valve Relays (no need for secondary booster)
• Span Continuously Adjustable (down to 20% of range)
• Air Consumption (at balance condition) 0.05 scfm max.
Changes in DP are transmitted mechanically to the flapper, which covers a small constant-feed nozzle. Any change in the position of the flapper will instantly change the nozzle pressure, which in turn controls the action of the 2-valve balanced relay to increase or decrease the output air pressure. A calibrated bellows assembly actuated by the output pressure serves to reposition the flapper mechanism and restore a state of equilibrium – in this manner, output air pressure varies in direct relation to the differential pressure applied to the instrument, or in direct proportion to the flow-rate. The relay is not affected by changes in output pressure and this makes it possible to maintain practically constant nozzle pressure at any output pressure.
Operating Span/Suppression (Linear-with-DP units only)
The operating span is continuously adjustable from 100- 20% of the DP range. Thus a unit with a differential pressure range of 0-100″ w.c. can be adjusted to provide a 3-15 PSI (207 mbar-1 bar) output signal (direct or reverse) for any span from 0-20″ w.c. to 0-100″ w.c. (0-50 mbar to 0-248 mbar) range. The operating span can be shifted anywhere within the range of the differential pressure unit to introduce suppression up to 80% of the range.
Barton® Pneumatic Transmitters are actuated by the Barton M199
Differential Pressure Unit (DPU) which is also available in a NACE certified version.
Cases available for Barton model 274A, 335A, 335P, 335T and 338E:
Barton® Pneumatic Transmitters are housed in a rugged, weatherproof case especially suited for use in corrosive fume environments. Since the pilot valve and nozzle exhaust
inside the case, continuous purging is achieved.