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Calculation of Pressure Regulators for Steam |
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Calculating the nominal diameter
To keep pressure drop and noise within acceptable limits, certain flow velocities
in the pipelines should not be exceeded. If no values have been specified we recommend
the following:
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Exhaust Steam |
25 m/s |
|
Saturated Steam |
40 m/s |
|
Super Heated Steam |
60 m/s |
These rough guidelines apply to pipe diameters from DN 80 up. For smaller diameters lower flow velocities should be used.
As in most cases the specific volume is not known, we use the following sufficiently accurate formula to calculate the volume:
Accordingly in our example the flow rates upstream and downstream of the valve are as follows (not taking into account the temperature drop caused by the pressure drop):
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m³/h |
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m³/h |
The pipeline diameter can be calculated using the following formula:
If in our example a maximum flow velocity of 25 m/s has been specified, the required pipeline diameters will be as follows:
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= 63 mm |
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= 79 mm |
We would therefore recommend pipes DN 65 upstream and pipes DN 80 downstream of the valve.
For a given nominal diameter the flow velocity can be calculated as follows:
In our example the flow velocities in the pipeline would be
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m/s |
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m/s |
For certain operating conditions a control valve may be selected whose nominal diameter is one or two sizes
smaller than the nominal pipeline diameter. Downstream of the valve the pipeline diameter may be increased
by one or two sizes depending on the flow velocity; this applies especially to valves designed for pilot line operation.
Continue
download the PDF-file:  Calculation of pressure regulators / PDF (156 kb)
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