23
7500 Series Manual
4.2.2 Flow Rate Curves
The enclosure pressure vs. flow rate curves below represent the EPV-7500....-01, 02, 03, and 04 vents. This
corresponds to the enclosure pressure and is independent of the valve used, provided the valve can deliver
the flow rate that is required.
The vent flow tables represent the flow rate and enclosure pressure for each vent with a safety margin
attached to the values. Enclosure pressure may be less than the tables below for actual measured value.
The values below do not take into account leakage from the enclosure; they represent a perfectly sealed
enclosure. In most applications, the enclosure will have leakage, which will require higher flow rate into
the enclosure to achieve the correct reading. This extra flow will depend on the leakage throughout the
enclosure.
There is no restriction of enclosure size for each vent, but leakage rate, flow rate, enclosure pressure, and
the 7500 maximum purge time of 254:59 should be considered when applying these vents.
The EPV-7500-…-01 is usually used on large enclosures because it has a higher flow rate and lower back
pressure within the enclosure than the other versions. This can reduce the purging time while keeping the
enclosure pressure low, which is important for a large enclosure. However, this vent leaks more pressure
through its flow control mechanism.
The EPV-7500-…-02 provides a better seal at the vent than the EPV-7500-…-01. The flow rate for purging is
less for the same enclosure pressure of the ‘-01’ version.
The EPV-7500-…03 provides the best seal for pressurization and should be selected for a smaller enclosure,
bottled air, or inert gas sources, and for increased conservation of the protective gas source. The flow rate is
less than the ‘-01’ and ‘-02’ versions but provides very low leakage.
The EPV-7500-PY-04 is similar to the EPV-7500-…03 vent and is used in the same applications, but it
is made out of polyoxymethylene and is lower in cost. The flow rate and enclosure pressure are slightly
different. See the tables below for exact values.
EPV-75000-...-01 Vent Flow vs. Enclosure Pressure
ft
3
/m Inches of water l/m mbar
5 1.28 141 3.19
7 1.44 198 3.59
10 1.64 283 4.09
12 1.80 339 4.48
15 2.10 424 5.23
17 2.30 481 5.73
20 2.53 566 6.30
25 2.95 707 7.35
30 3.50 849 8.71
35 4.15 991 10.33
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