Spirax Sarco BXRA is a normally closed, single seat self-acting control valve. The BX range of two-port valves is used in conjunction with Spirax Sarco SA control systems to provide a self-acting temperature control unit.

Available Types

• BXRA: Normally closed, single seat.
• BX: Normally open, single seat with four different orifice sizes (BX2, BX3, BX4, and BX6).
• Sizes and pipe connections: ½" screwed BSP (BS 21 parallel) or NPT.

Materials

No.	Part	Material	Standard
1	Body	Gunmetal	CC491 K or CC491 K M
2	Valve closure member	Stainless steel	AISI 440B
3	Valve seat ring	Stainless steel	BS 970 431 S29
4	Valve seat gasket	Copper	BS 2870 C102
5	Ball return spring	Stainless steel	BS 2056 302 S26
6	Main return spring	Stainless steel	BS 2056 302 S26
7	Bonnet	Brass	BS 2872 CZ 122
8	Bonnet gasket	Reinforced exfoliated graphite

Design Conditions

Condition	Value
Body design conditions	PN25
Maximum design temperature (fitted to a Spirax Sarco spacer)	260 °C (500 °F)
Maximum design temperature (fitted directly to an actuator)	232 °C (450 °F)
Maximum differential pressure (BXRA)	10.3 bar (150 psi)
Maximum differential pressure (BX)	17.2 bar (250 psi)
Designed for a maximum cold hydraulic test pressure of	38 bar g (550 psi g)

WARNING

The product must not be used in the restricted region shown in the pressure/temperature limits chart. When the valve is operated with a self-acting temperature control system in this region, a Spirax Sarco spacer must be used.

Kv Values

Type	BX2	BX3	BX4	BX6	BXRA
Kv	0.38	0.64	1.03	1.65	0.59

For conversion: $C_v (UK) = K_v \times 0.963$, $C_v (US) = K_v \times 1.156$

Capacities

• For saturated steam sizing capacities, see TI-GCM-08.
• For water sizing capacities, see TI-GCM-09.

Dimensions and Weight

Size	A	B	Weight
½"	80 mm (3.15")	83 mm (3.15")	0.7 kg (1.54 lb)

Installation and Commissioning

INFO

Before actioning any installation observe the general safety information. The valves are for use with Spirax Sarco EL and SA control systems Types 121, 122, 123 and 128. (Types 122 and 128 are not suitable for valves above 1"/DN25).

The valve should always be fitted in a horizontal pipeline with the flow in the direction indicated by the arrow marked on the body, with the sensor in a vertical plane below the pipeline. A suitable strainer should always be fitted upstream of the valve. Additionally on steam installations, a separator should be fitted before the valve, plus a steam trap set on applications where condensate may accumulate upstream of the valve.

WARNING

The SA control system actuator must be securely connected to the valve via the screwed connection on the bottom of the valve and the half union coupling on the actuator before any fluid is allowed to pass through the valve. Similarly, the actuator should not be disconnected from the valve until the valve itself is fully isolated. It is important that line stresses (e.g. expansion or inadequate supporting of the pipe) are not imposed on the valve body.

Bypass Arrangements: It is recommended that isolating valves be fitted upstream and downstream of the control valve together with a manual regulating valve to bypass the group. The process may then be controlled by the bypass valve while the control valve is isolated for maintenance purposes.

Permanent Bleed

BMRA and BXRA valves are normally closed. When used as a cooling control it may be necessary to create a permanent flow over the sensor. In this case, this can be achieved by installing a small bore bypass around the valve. A 6 mm line will usually be adequate with the manual valve about one turn open.

Maintenance

WARNING

Laminated gaskets: The metal foil sheet used to reinforce gaskets is very thin and sharp. Care should be taken when handling to avoid the possibility of cuts or lacerations to fingers or hands.

Routine maintenance procedures:

• 24 hours operation: After 24 hours service check pipework connections and flange bolts for tightness.
• Annually: The valve should be inspected for wear and tear, replacing any worn or damaged parts such as valve plug and stem, valve seat.

General maintenance information:

• The valve faces must be kept clean.
• The strainer should be cleaned at regular intervals to ensure that the flow to the valve is clean and unrestricted.
• If at any time it is necessary to take the valve out of the line for servicing, then the appropriate safety precautions need to be adhered to.

Spare Parts

The available spare parts are the valve seat assembly and the gasket set.

Spare Part	Items Included
Valve seat assembly (BX and BXRA)	3, 4, 6, 8
Gasket set (packet of 3 each)	4, 8

Recommended tightening torques:

• Valve seat (Item 3): 18 A/F, 40 - 50 N m (30 - 37 ft lbf)
• Bonnet (Item 7): 40 - 50 N m (30 - 37 ft lbf)