Definition of technical terms used for control valves

General information

Product limitations

This is a combination of the product body and end connections and is the term used to describe

the pressure containing envelope of the product.

The PN is the nominal working pressure / temperature (which is dependant on materials, design

and working temperatures/pressures) that can be tolerated by the body of the product.

This is the maximum allowable pressure that the body of the product can withstand at a given

temperature.

This is provided by the manufacturer when it is less than the maximum design pressure. For

example the maximum design pressure may be reduced to the pressure limitation of the lowest

rated option chosen.

This is dependant upon the chosen actuator up to the maximum design pressure of the product.

This is the maximum allowable temperature to which the body of the product can be raised

permanently, at a given pressure.

This is the maximum temperature for correct operation of the product. This is determined by the

lowest rated option chosen.

This is the minimum documented temperature the body of the product can withstand.

This is the minimum temperature for correct operation of the product.

Designed for a maximum cold

hydraulic test pressure of __ bar g Note: When Spirax Sarco have tested the product in an alternative form than that supplied, a

or psi g

lower pressure will be given (see Typical pressure/temperature limits diagram below).

Body

Nominal pressure (PN)

Maximum design pressure

Maximum operating pressure

Maximum differential pressure

Maximum design temperature

Maximum operating temperature

Minimum design temperature

Minimum operating temperature

This is a cold hydraulic test applied to the body as supplied.

A standard layout for the Pressure / temperature limits

information is shown opposite.

For further layouts, depending on space available in the TI

or IMI, are shown on pages 4 and 5.

Pressure / temperature limits

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A

D

B

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region.

The product should not be used in this region or beyond

its operating range as damage to the internals may occur.

A-B-C Flanged PN25.

A-D-E Flanged PN16.

Note: As standard the XYZ series two port control valves are

supplied with PTFE stem seal and metal-to-metal seats.

Steam

saturation

curve

E

C

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Pressure bar g

The product must not be used in this region.

High temperature packing is required for use in this

Body design conditions

Maximum design pressure

Maximum design temperature

Minimum design temperature

As standard

Maximum

With high temperature

operating

packing

PN25

25 bar g @ 120 °C

350 °C @ 17.5 bar g

-20 °C

250 °C @ 22 bar g

300 °C @ 20 bar g

350 °C @ 18 bar g

11.4.8

temperature

With high temperature

bolting and packing

Minimum operating temperature

Note: For lower operating temperatures consult Spirax Sarco.

Maximum differential pressure

See relevant actuator TI

Designed for a maximum cold hydraulic test pressure of 37.5 bar g

Note: As supplied the test pressure must not exceed 25 bar g

-10 °C

TI-S24-41 CH Issue 3

Page 3 of 5

Pressure / Temperature Limits for Control Valves

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p

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