ASME PTC 25:2001 pdf free download

ASME PTC 25:2001 pdf free download.PRESSURE RELIEF DEVICES.
4.1 GENERAL
This Section describes the instruments, methods, procedures, and precautions that shall be used in testing pessure reliel devices under this Code. The Performance Test Code Supplements on Instruments and Apparatus provide authoritative general information concerning instruments and their use, and may be consulted for such information.
4.2 FLUID CONDITIONS, TEST CONDITIONS, AND INSTRUMENTATION
4.2.1 Atmospheric Pressure. Barometric pressure shall be measured with a barometer (see ASME PTC 19.2). In calculations involving the capacity of pressure relief devices having a flow-rating pressure of 20 psig or higher, the use of the mean barometric pressure at the test site satisfies the accuracy requirements of this Code. In such cases, the recorded pressure may 1w the mean barometric preure.
4.2.2 Temperature. Instructions on thermometers or thermocouples and associated instruments are given in ASME PTC 19.1. except that commi’rc:ial metal-encased thermometers shall not be used in tests conducted under this Code. Other means of temperature measurement and indication may be used, provided they are of the same or greater degree of accuracy as for those described therein.
fa) Depending on operating conditions, or convenience, the temperature may be measured with certified or calibrated liquid-in-glass thermometers. bimetallic thermometers, resistance-type thermometers, or thermocouples. All of the above may be inserted directly into the pipe or into wells except for liquid-in-glass thermometers, which must be inserted into wells. The installation of the temperature-measuring device directly into the pipe, without the addition of a well, is desirable for temperatures below 3009.
b) The following precautions shall he taken when making any temperature measurements.
(1) No significant quantity of heat shall be transferred by radiation or conduction to or from the temperature-measuring device other than by the temperature of the medium being observed see
ASMI PTC 19.3).
(2) The immediate vicinity of the point of insertion and the external projecting parts shall be insulated.
(3) The temperature-measuring device shall extend across the center line in pipes of small diameter or shall be inserted at least 6 in. into the fluid stream in pipes over 12 in. in dianwter.
(4) Temperature-measuring devices installed in FiiW’ carrying u mprt’ssilk’ tlUi(lS shall, wlwws’er possible, be installed at locations where the maximum fluid velocity during any flow measurement does not exceed 100 ft/sec. Where such art installation is not possible, it may be necessary to correct the temperature readings to the appropriate static or total temperature see ASME PTC 19.5).
(5) The temperature-measuring devices shall be inserted in locations so as to measure temperatures which are representative of the flowing medium as described under test arrangements.
(C) When measuring temperatures with a mercury. in-glass thermometer, the instrunwnt shall have an etched stem. When the measured temperature differs from the ambient by more than 10°F, and the mercury is exposed, an emergent stem correction shall be made