ITT Barton Model 288

 These 6" differential pressure-indicating switches energize alarm and control circuits at predetermined limits of flow through pipelines, liquid levels within pressurized vessels, or pressure losses across devices such as filters. They are used in conjunction with a primary DP element, such as an orifice or venturi, to monitor flow rates.

Weatherproof, ITT Barton­ Models 288, & 288A, are DP Indicating Switches. The 288A and 288C have NEMA-4 watertight die-cast aluminum cases (finished with a weather-resistant black epoxy resin paint). The durable lexan lens is secured in the bezel with an elastomer ring to reduce the possibility of accidental breakage. This ring also acts as a seal between the bezel and the case to ensure a moisture, fume and dust-free atmosphere for the jeweled indicator movement and switch mechanism. 

  The die-cast aluminum indicating switch housing is attached directly to the actuating unit (224 DPU). The indicating switch assembly consists of a drive arm with an integral switch actuator cam, linkage, and a jeweled movement assembly to which the indicating pointer is attached. Also included are the Micro switches and associated linkages, switch set point indexes, and set point locks. Changes in differential pressure are sensed by the differential pressure units below and transmitted as rotary motion through the torque tube to the drive arm assembly of the indicating switch. The linkage and movement assembly responds to the drive arm assembly's action to position the scale pointer to the indication relative to the differential pressure sensed by the DPU. It simultaneously actuates the switch when the desired setpoint is reached. It does this because the drive arm has an integral switch actuating cam and is attached to the torque tube shaft, which rotates between 8 and 10 degrees with the motion of the torque tube shaft. Two cam follower roller/actuator arm assemblies, one for each switch, respond to drive arm movement by opening and closing the switches as they ride on and off the cam. The levels of differential pressure at which the switches actuate are adjustable with high and low alarm switch adjustment indexes below the scale plate.
Minor adjustments to the switch set point can be made without removing the scale plate. Barton Models 288A/288C can have up to 4 alarm switches, but one or two alarm switches are standard. Each switch can be connected to operate normally-opened or normally-closed. The switches set points are adjustable between 5-95% of the scale range. SPDT and DPDT switch configurations are available. 

Housings and Safe Working Pressures

Forged Brass (FG Brass)......................SWP 500 PSI (34.5 bar)

Brass ....................................................SWP 1000 PSI (68.9 bar)

Carbon Steel ........................................SWP 1500, 3000, & 6000 PSI (103.4, 206.9 & 413.8 bar)

316 Stainless Steel...............................SWP 500,1500, 3000, & 6000 PSI (34.5, 103.4, 206.9 & 413.8                                                                  bar)

Cast Aluminum ....................................SWP 400 PSI (27.6 bar)

Alloy Steel ............................................SWP 10,000 PSI (689.5 bar)

Bellows Material

316 Stainless Steel

Beryllium Copper 

Inconel 625

DP Ranges

0-30" W.C to 0-1000 PSI (ranges limited by the SWP and housing materials chosen.)

Actuating Unit.......................................Model 224 DPU

Dial Size.................................................6 Inches (150mm) Diameter

Temperature Limits.............................-40°F/C to + 180°F (+82°C) (+40°F minimum for water filled units- "D" Fill)

Adjustments........................................ Zero and Span (Micrometer-type)

Mounting..............................................Flush/Panel, Wall, and 2"Pipe/Yoke, 

Indicator Case.....................................Aluminum Alloy, Powder Coated, Enamel or Epoxy Finish

Lens......................................................Polycarbonate

O-Rings (Wetted).................................Buna-N, Viton, or EPT (Special available upon request)

Overall Dimensions.............................per configuration and DPU housing rating

Weight ..................................................6 to 9.5 lbs (approx.) Weight depends on DPU                                                                  configuration/materials.

Accuracy (DP Range)

Switches Disengaged.........................................±1% of full scale

At Switch Actuation........................................... ±1.5% of full scale

Switch Deadband ............................................. 5% of full scale

Repeatability.......................................................0.25% of full scale

Bellows Construction - Individual diaphragms, stamped and formed from 316 stainless steel, Inconel 625, or beryllium copper, are assembled using highly specialized techniques. The results are exacting linearity characteristics, a long cycle life, and freedom from effects of work hardening commonly encountered with the hydraulically formed or mechanically rolled type bellows. 

Torque Tube eliminates the possibility of leakage and the need for lubrication. The needle bearing (inboard end) and ball bearing (on follower drive arm) operate with a minimum of friction, resulting in a high degree of sensitivity over the unit's life. 

Temperature Compensator—An auxiliary free-floating bellows attached to the HP bellows automatically protects the unit from zero/calibration drift when the ambient temperature changes.  

Self-Draining/Venting Connection on the top and bottom of the pressure housing provides automatic draining of liquids or venting of gases.

Calibration Springs—The strength of the range springs determines the differential pressure range of the unit. Each range spring assembly is stamped with the DP range it produces. Range springs have an extremely low hysteresis characteristic and exceptional temperature stability.