General information Product limitations
7
Definition of technical terms used for control valves Body
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.
Nominal pressure (PN)
Maximum design pressure
Maximum operating pressure
Maximum differential pressure
Maximum design temperature
Maximum operating temperature
Minimum design temperature Minimum operating temperature Designed for a maximum cold hydraulic test pressure of __ bar g or psi g
This is the minimum temperature for correct operation of the product.
This is a cold hydraulic test applied to the body as supplied. Note: When Spirax Sarco have tested the product in an alternative form than that supplied, a lower pressure will be given (see Typical pressure/temperature limits diagram below).
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
A
D
B
Steam saturation curve
E
C
Pressure bar g
7.4 7
The product must not be used in this region. High temperature packing is required for use in this 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.
Body design conditions
PN25
Maximum design pressure
25 bar g @ 120 °C 350 °C @ 17.5 bar g
Maximum design temperature Minimum design temperature
11.4.8
-20 °C
As standard
250 °C @ 22 bar g
Maximum operating temperature
With high temperature packing With high temperature bolting and packing
300 °C @ 20 bar g
350 °C @ 18 bar g
Minimum operating temperature -10 °C 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
TI-S24-41 CH Issue 3
Page 3 of 5
Pressure / Temperature Limits for Control Valves
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