EN 334-2005 pdf download.Gas pressure regulators for inlet pressures up to 100 bar.
A.2 Test methods
A.2.1 Direct acting gas pressure regulator
In this type of regulator it is necessary to vary the pressure on one side of the detector element in order to move the control member from the open position to the closed position.
The test method comprises the following steps:
— set the regulator at the minimum value of the set range Wd following the manufacturer’s instructions;
— increase the pressure in the casing of the actuator from art external source until the control member reaches its closed position and verify the internal sealing at the minimum and maximum inlet pressures (internally impulsed regulators may have to be modified);
— vent the pressure from the body;
— slowly reduce the pressure in the casing of the actuator until the control member reaches the required open position (i.e. the one relevant to the expected maximum accuracy flow rate) and measure the pressure corresponding to each 10 % increase in the valve travel:
— slowly increase the pressure in the casing of the actuator until the control member reaches the lock-up position and measure the pressure corresponding to each 10 % decrease in the valve travel;
— establish the closed position by the verification of internal sealing;
— calculate for each position of the control member the volumetric flow rate Q using the method detailed in
6.5.
With balanced moving parts (i.e. no variation in the thrust on the moving parts against changes in inlet pressure Pe) all measured values of the pressure, except that for the closed position, should be within the expected accuracy class AC.
The measured value of the lock-up pressure p should be within the expected lock-up pressure class SG. The hysteresis can be verified by measuring the maximum difference in pressure for the same position of the control member.
The calculated value of flow rate giving maximum accuracy should be greater than or equal to that specified by the manufacturer (see Figure A.1).
With unbalanced moving parts the same method should be used , with account taken of the unbalanced thrust (see Figure Al).
A.2.2 Pilot controlled gas pressure regulators
With this type of regulator it is necessary to vary the motorization pressure in the motonzation chamber in order to move the control member from the closed position to an open position and vice versa. The thrust created by the motorization pressure is normally balanced by the load of a spring. The motorization pressure is supplied by the pilot. The pilot controls the supply of the motorization gas according to the value of the control deviation in such a way as to keep the outlet pressure as close as possible to its set point.
Therefore, In both a regulator and pilot with moving parts balanced (i.e. no variation in the thrust on the moving parts with changes in inlet pressure) it is possible to classify the performance of the system i.e. the regulator with its pilot, by measuring the variation in outlet pressure against the position of the control member from the closed position to a specific valve travel. The test method should be established in detail according to the specific design of the regulator.
In the following test method reference should be made to the functional diagram given in Figure A.3.
Figure A.4 shows the relationship between the valve travel, motorization pressure Pm and the flow through the process line Qf and the outlet pressure of the system Pd including the regulator and its pilot.
The test method comprises the following steps:
a) set the pilot at the minimum value of the set range Wd following the manufacturer’s instructions;
b) feed the pilot from an external source using the applicable fixture at minimum inlet pressure Pumjn and exhaust the gas from the chamber where both process and sensing lines are connected:
c) keep the regulator in the closed position using upstream inlet pressure. The inlet and outlet end connections may be sealed by using blind flanges:
d) verify internal sealing of the regulator with Qf = 0 at minimum and maximum inlet pressure pu
e) regulate the inlet pressure at Pumjn.EN 334-2005 pdf download.
EN 334-2005 pdf download
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