systems. "Standard" pressure switches are typically
installed downstream of the retard chamber of the
alarm valve alarm line trim.
**************************************************************************
Unit shall include a 13 mm 1/2 inch NPT male pipe thread, two 13 mm 1/2 inch
conduit knockouts, and two sets of SPDT (Form C) contacts. The switches
shall be factory adjusted to transfer the contacts at 27.6 to 55.1 kPa 4 to
8 psi on rising pressure. Unit shall include a water-tight NEMA 4 die-cast
aluminum housing with a tamper resistant cover which requires a special key
for removal. The cover shall be provided with a tamper switch which shall
operate upon removal of the cover. Units used on wet-pipe systems shall
have an adjustable, instantly recycling pneumatic retard to prevent false
alarms due to water pressure variation. Retard adjustment shall be factory
set at approximately 20-40 seconds and adjustable between 0-90 seconds.
2.21.2
Vane-type Waterflow Switch
**************************************************************************
NOTE: Vane-type flow switches cannot be used on
preaction, deluge or other system piping which is
not normally filled with water or AFFF solution.
**************************************************************************
Assembly shall consist of a cast aluminum pipe saddle housing an
electro-mechanical device to which is attached a flexible, low-density
polyethylene paddle. The paddle shall conform to the inside diameter of
the fire protection pipe and sense water or solution movements. The
waterflow indicator shall be capable of detecting a sustained flow
exceeding 0.63 L/second 10 gpm. Assembly shall contain a pneumatic retard
device adjustable from 0 to 90 seconds to reduce the possibility of false
alarms caused by transient flow surges. The unit shall include two sets of
SPDT (Form C) contacts. The unit shall be equipped with a silicone rubber
gasket to assure positive water seal and a dustproof cover and gasket to
seal the mechanism from dirt and moisture.
2.21.3
Heat Detector-Spot Type
**************************************************************************
NOTE: Include description of the type of heat
detection shown on drawings. Delete the
inapplicable type.
**************************************************************************
Detector shall be weatherproof, of the rate-compensation type with a
nominal temperature rating of [76] [_____] degrees C [170] [_____] degrees F.
Detector shall be listed or approved for spacing between detectors as
shown. Detectors listed or approved as "rate anticipation" type will be
accepted. Detectors utilizing the fixed-temperature, rate-of-rise, or
combination fixed-temperature/rate-of-rise principles will not be accepted.
Six spare detectors of each type and temperature rating shall be provided.
2.21.4
Continuous Linear Thermal Detector
Detector shall be line-type electrical conductivity fixed temperature
coaxial wire capable of sensing temperature changes along its entire length
and operate over a wide range of temperatures. The detector cable shall be
constructed of a center conductor having a maximum diameter of 2.20 mm
0.087 inch, a ceramic thermistor core and an outer metallic sheath. The
SECTION 13955A
Page 25
Previous Page
