Description

The KB71 two-port control valve is used in conjunction with Spirax Sarco self-acting controllers to provide a self-acting temperature control unit.

Available Types

Model	Description
KB71	Normally open valve, phosphor bronze bellows, threaded connection

Note: Pressure balancing bellows enables the valve to operate against higher differential pressures.

Standards and Certification

• Standards: These products fully comply with the requirements of the European Pressure Equipment Directive 97/23/EC
• Certification: As standard these products are available with a manufacturers' Typical Test Report
• Note: All certification/inspection requirements must be stated at the time of order placement.

Sizes and Pipe Connections

• BSP (BS 21 parallel) or NPT:
  • DN25 (1"), DN32 (1¼"), DN40 (1½") and DN50 (2")

Pressure/Temperature Limits

Parameter	Value
Body design conditions	PN16
Maximum design pressure	16 bar g @ 220°C
Maximum design temperature	220°C @ 10 bar g
Minimum design temperature	-10°C
Maximum operating temperature	220°C
Minimum operating temperature	0°C

Note: For lower operating temperatures consult Spirax Sarco.

Maximum Differential Pressure (bar):

Model/Size	DN25	DN32	DN40	DN50
KB71	10.3	9.0	8.2	6.9

Designed for a maximum cold hydraulic test pressure of: 24 bar g

Important

The product must not be used in the shaded region of the chart.

Kv Values

Size	DN25	DN32	DN40	DN50
KB71	9.80	16.48	23.70	34.00

Conversion formulas: Cv (UK) = Kv × 0.963 | Cv (US) = Kv × 1.156

Capacities

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

Materials

No.	Part	Material	Standard
1	Body	Ductile iron	QT450-10
2	Bonnet	Ductile iron	QT450-10
3	Valve head	Stainless steel	BS 970 431 S 29
4	Valve seat ring	Stainless steel	BS 970 431 S 29
5	Valve seat gasket (DN15-DN25)	Mild steel	BS 1449 CS 4
5	Valve seat gasket (DN32-DN50)	Reinforced exfoliated graphite	-
6	Return spring	Stainless steel	BS 2056 302 S 26
7	Stem	Phosphor bronze	BS 2874 CZ 121
8	Bonnet gasket	Reinforced exfoliated graphite	-
12	Bonnet studs	Steel	BS 4439 Gr. 8.8
13	Bonnet nuts	Steel	BS 3692 Gr. 8
13	Bellows	Phosphor bronze	EN 12449 Cu Sn 6
14	Bellows gasket	Reinforced exfoliated graphite	-
15	Bonnet bush	Brass	BS 2874 CZ 121
16	Plunger	Brass	BS 2874 CZ 121

Dimensions and Weights (Approximate) in mm and kg

Size	A	A1	B	C	Weight
DN25 - 1"	136	160	138	51	3.4
DN32 - 1¼"	144	180	152	51	5.7
DN40 - 1½"	150	200	152	62	6.9
DN50 - 2"	180	230	152	71	8.8

Spare Parts

The spare parts available are shown in solid outline. Parts drawn in a grey line are not supplied as spares.

KB71 Available Spares

Spare Part	Consists of
Valve seat assembly (excluding bellows and stem assembly)	L, U, G
Bellows and stem assembly	G, L, N, H
Set of all gaskets	B, C, E, L, U, G
Set of bonnet studs and nuts (set of 4)	S

How to order spares: Always order spares by using the description given in the column headed 'Available spares' and state the size and type of valve. Example: 1 - Valve seat assembly for a Spirax Sarco DN32 KB71 self-acting control valve.

Safety Information, Installation and Maintenance

For full details see the Installation and Maintenance Instructions (IM-S21-01) supplied with the product.

Installation note: The valve should be fitted in a horizontal line with the actuator vertically below the pipeline.

How to Order

Example: 1 off Spirax Sarco 1¼" KB71 ductile iron self-acting control valve with phosphor bronze bellows, BSP threaded connection.