ASME PTC 25:1994 pdf free download.Pressure Relief Devices.
(f) Decrease inlet pressure slowly and again record reseating pressure of valve and back pressure.
(g) In most instances, it is desirable, or a requirement. that the valve be tested over a given range of back piessure. In such cases, it is convenient if the value of back pressure chosen in (a) above be either the lowest or highest of this range. Back pressure may then be increased or decreased in increments. repeating (a) through (h) above at each incremental value.
4.15 Tesling WIth Built-Up Back Presaure (Fig. )
(a) Increase the pressure at the valve inlet. During the pressure interval starting at 90% of the expected set pressure, the rate of pressure increase shall not exceed 2.0 psi)sec. or whatever lesser rate of increase is necessary for the accurate reading of the pressure Observe and record the set pressure of the valve and any other desired or pertinent characteristics.
(b) Continue increasing the pressure at the valve inlet until the valve remains open, Adjust built-up back pressure to desired value. Observe the action of the valve. Gradually decrease the inlet pressure until the valve closes. Record the reseating pressure of the valve and back pressure. Observe the action of the valve.
(C) Repeat paras. (a) and (b), recording set and reseating pressures, and back pressure, until all are established and stabilized.
(d) Establish and maintain flow-rating pressure until flow instruments and back-pressure gage indicate a steady-state condition.
(e) Record the following:
(1) valve-inlet pressure;
(2) valve-disk lift
(3) liquid-inlet temperature;
(4) flow-meter differential pressure;
(5) back pressure.
(g) Decrease inlet pressure slowly and again recod reseating pressure of valve and back pressure.
(h) In most Instances, it is desirable, or a requirement, that the valve be tested over a given range of back pressure. In such cases, it is convenient it the value of back pressure chosen in para. 4.8.4(a) be either the lowest or highest of this range.
ASME PTC 25:1994 pdf free download
