BPC32 Balanced Pressure Thermostatic Steam Trap

BPC32 balanced pressure thermostatic steam trap for steam systems

Spirax Sarco BPC32 is a carbon steel, maintainable balanced pressure thermostatic steam trap for removing condensate from steam systems. Its straight body connections and integral flat strainer screen bring the trap and its first filtration stage into one serviceable assembly. This makes the model relevant where a steam trap must be inspected, cleaned and returned to service without treating the complete unit as a disposable component.

The BPC32 is intended for a defined engineering duty. The official installation information identifies steam, air and water or condensate in Group 2 of the Pressure Equipment Directive as the intended fluid groups. Use with another fluid requires confirmation of material compatibility and operating suitability before selection. The pressure, temperature, differential pressure and return-line conditions also need to be checked together; a model number by itself is not a complete duty specification.

What the BPC32 is designed to do

A balanced pressure thermostatic trap uses a capsule containing a small quantity of special liquid with a boiling point below that of water. At start-up, when the surrounding conditions are cold, the capsule is relaxed and the valve is open. This allows air to leave the system freely, which is an important feature of the balanced pressure principle. As condensate approaches steam temperature, heat passes into the capsule liquid. The liquid boils, its vapour pressure expands the capsule and the valve closes.

When the trap loses heat, the capsule fill condenses and the capsule contracts. The valve then opens to release condensate until the cycle repeats. The BPC32 therefore responds to the thermal condition around the capsule rather than relying on a fixed orifice. The selected capsule fill changes the approximate discharge temperature below steam saturation: the standard STD fill is about 12 degrees C below saturation, while SUB is about 24 degrees C below saturation and NTS is about 6 degrees C below steam temperature.

The manufacturer describes the trap as unaffected by waterhammer. That statement does not remove the need to design the connected pipework correctly. Drainage points, the inlet drop leg, the discharge route, support, isolation and return-line pressure all remain part of the system review. The BPC32 should be selected for the actual condensate load and pressure difference available at the trap, including start-up and low-load cases.

Serviceable construction and integral filtration

The carbon steel body has straight connections and an integral flat strainer screen ahead of the working parts. The cover, capsule, spacer plate, valve seat and spring are accessible during planned service. The screen can be cleaned or replaced as part of the maintenance procedure, and the valve seat and capsule can be inspected without replacing the complete body. The cutaway illustrates this arrangement and helps distinguish the BPC32 assembly from a separate line-mounted filter.

The technical information identifies carbon steel DIN 17243 C22.8 (W/S 1.0460), ASTM A105N for the body and cover, stainless steel for the capsule, stainless steel BS 970 431 S29 for the valve seat and AISI 304 stainless steel for the screen. The cover gasket is stainless steel reinforced exfoliated graphite. Stainless steel M10 x 30 A2-70 cover bolts, a carbon steel strainer cap and a stainless steel BS 1449 304 S16 strainer cap gasket complete the principal listed parts. These designations should be checked against the actual fluid, corrosion environment and temperature during procurement.

Optional arrangements must be confirmed when ordering. The documented capsule fills are STD, SUB and NTS. The product information also describes an optional BDV1 or BDV2 blowdown valve on the strainer cap, or a prepared 3/8 inch BSP T Rp (ISO 7-1) or NPT connection that can be drilled, tapped and plugged as specified. An optional aluminium insulating cover can reduce the influence of excessive heat loss caused by wind, rain or low outside temperatures. These options affect the installed configuration and the available maintenance clearance.

For broader component selection, the steam strainers and filters category is useful when a separate upstream or downstream filtration stage is being considered. It should not be used to reinterpret the BPC32 integral screen as a separate filter product.

Pressure, temperature and differential pressure limits

The BPC32 has a PN40 body design condition. Its maximum allowable pressure is 50 bar g at 50 degrees C, and its maximum allowable temperature is 400 degrees C at 35 bar g. For saturated steam service, the maximum operating pressure is 32 bar g at 281 degrees C, with the corresponding maximum operating temperature of 281 degrees C at 32 bar g. These are conditional limits. The pressure and temperature point must remain within the applicable region of the official pressure/temperature chart rather than being checked as two independent maximum values.

The minimum allowable temperature is -60 degrees C and the minimum operating temperature is 0 degrees C. The source advises consultation for lower operating temperatures. The cold hydraulic test pressure is designed up to 75 bar g; this is a test value and must not be treated as an operating pressure. The technical information verifies full-vacuum use for the documented screwed, socket weld, butt weld and flanged connections, while other arrangements require confirmation.

The available operating differential pressure is the pressure difference that drives condensate through the trap. It should be established at the trap inlet and outlet for normal operation, start-up, shutdown and the lowest expected load. The capacity chart in the technical section is a reference curve rather than a universal capacity rating. Final selection needs the actual condensate load, pressure difference and connection configuration, with any shared curve labels interpreted only for the BPC32 case.

Choosing the Spirax Sarco BPC32 for a steam system

The documented nominal sizes are 1/2 inch, 3/4 inch and 1 inch. The connection options include screwed BSP T Rp (ISO 7-1) or NPT, socket weld ends to BS 3799, butt weld ends to EN 12 627, and DN15, DN20 and DN25 flanged connections to the listed EN 1092 PN40, ASME B 16.5 Class 150 or Class 300, and JIS/KS standards. Select the connection standard to match the pipework and local installation practice; do not infer a connection from nominal size alone.

A suitable selection review starts with the condensate load and available differential pressure, then checks the saturated steam pressure, maximum and minimum temperatures, return-line pressure and the possibility of vacuum conditions. Confirm the capsule fill and whether the optional blowdown or insulation arrangement is needed. The BPC32 is a component in the wider steam trap selection process, so the choice should also consider whether another trap operating principle better matches the duty.

The BPC32 should not be selected for a duty outside its documented pressure/temperature envelope or without checking the fluid group. If the operating limit of the trap is lower than the system limit, the system needs an appropriate safety device. External stresses from connected pipework must be considered by the installer, and protection covers and name-plate film should be removed where appropriate before high-temperature service.

Installation and discharge integration

The installation guide allows the BPC32 to be installed horizontally or vertically, provided the installation situation and direction of fluid flow are correct. A drop leg immediately before the trap is preferred, typically 150 mm (6 inches). Without a suitable drop leg, low-load steam can pass over condensate in the bottom of the pipe and reach the trap. Upstream and downstream isolation valves provide the controlled boundary needed for inspection, cleaning and replacement.

Where condensate enters a return line with backpressure, fit a downstream non-return valve so the steam space cannot flood when inlet pressure falls or steam is shut off. The relevant steam check valve selection should be based on the return system and flow conditions. Where the BPC32 discharges to atmosphere, direct the outlet to a safe location. The installation information warns that the discharge may be at 100 degrees C and recommends a steam diffuser to cushion high-velocity discharge and reduce noise and erosion.

Open isolation valves slowly until normal conditions are reached, then check for leaks and correct operation. Allow sufficient room to remove the cover: the minimum cover withdrawal distance is 37 mm (1 1/2 inches). The connected system should provide safe access, adequate lighting, suitable lifting arrangements where needed and protection against hot surfaces, hazardous fluids and pressure release.

Maintenance access and ordering checks

Maintenance can be completed with the BPC32 in the pipeline after the supply and return sides have been isolated, pressure has been safely normalised to atmosphere and the trap has cooled. Joint faces must be clean during reassembly. The documented service work includes checking or replacing the capsule and seat assembly, cleaning or replacing the integral flat strainer screen, fitting new gaskets where required and tightening the parts to the specified torque. Use suitable tools, genuine replacement parts and appropriate protective equipment.

Before an order is released, record the model, size, connection standard, capsule fill, normal and maximum pressure, temperature, condensate load, available differential pressure, expected return-line backpressure and discharge arrangement. State certification and inspection requirements at order placement; EN 10204 3.1 certification is available when requested. This information gives the final configuration a traceable basis and avoids treating a nominal connection or a capsule option as a complete process specification.

BPC32 selection summary

• Carbon steel, maintainable balanced pressure thermostatic steam trap with straight connections and an integral flat strainer screen.
• STD, SUB and NTS capsule fills for different approximate discharge temperature relationships.
• 1/2 inch, 3/4 inch and 1 inch sizes with BSP T Rp (ISO 7-1), NPT, socket weld, butt weld or documented flanged connection options.
• PN40 body design condition, 32 bar g at 281 degrees C maximum saturated-steam operating condition and 75 bar g maximum designed cold hydraulic test pressure.
• Horizontal or vertical installation with correct flow direction, a preferred 150 mm drop leg, isolation for service and non-return protection where return-line backpressure occurs.

When specifying the Spirax Sarco BPC32, retain the process data, connection standard, capsule fill and certification requirement with the model reference. The technical information and installation guide that follow provide the detailed limits, tables, diagrams, safety conditions and maintenance sequence needed for the final review.