BS 54-5:2001 pdf download – Fire detection and fire alarm systems — Part 5: Heat detectors — Point detectors
5.1.2 Operating conditions for tests If a test method requires a specimen to be operational, then the specimen shall be connected to suitable supply and monitoring equipment with characteristics as required by the manufacturer’s data. Unless otherwise specified in the test method, the supply parameters applied to the specimen shall be set within the manufacturer’s specified range(s) and shall remain substantially constant throughout the tests. The value chosen for each parameter shall normally be the nominal value, or the mean of the specified range. If a test procedure requires a specimen to be monitored to detect any alarm or fault signals, then connections shall be made to any necessary ancillary devices (e.g. through wiring to an end-of-line device for conventional detectors to allow a fault signal to be recognized). NOTE: The details of the supply and monitoring equipment and the alarm criteria used should be given in the test report.
5.1.3 Mounting arrangements The specimen shall be mounted by its normal means of attachment in accordance with the manufacturer’s instructions. If these instructions describe more than one method of mounting then the method considered to be most unfavourable shall be chosen for each test.
5.1.4 Tolerances Unless otherwise stated, the tolerances for the environmental test parameters shall be as given in the basic reference standards for the test (e.g. the relevant part of IEC 60068). If a requirement or test procedure does not specify a tolerance or deviation limits, then deviation limits of ±5 % shall be applied.
5.1.5 Measurement of response time The specimen for which the response time is to be measured shall be mounted in a heat tunnel as described in 5.1.3 and annex A. It shall be connected to suitable supply and monitoring equipment in accordance with 5.1.2. The orientation of the specimen, relative to the direction of airflow, shall be that which gave the maximum response time in the directional dependence test 5.2, unless otherwise specified. Before the measurement, the temperature of the air stream and the specimen shall be stabilized to the temperature specified in the applicable test procedure. The measurement is then made by increasing the air temperature in the heat tunnel linearly with respect to time, at the rate of rise specified in the applicable test procedure until the supply and monitoring equipment indicates an alarm or until the upper limit of response time for the test is exceeded. During the measurement the air flow shall be maintained at a constant mass flow, equivalent to (0,8 ± 0,1) m s -1 at 25 °C, and the air temperature shall be controlled to within ±2 K of the nominal temperature required at any time during the test (see annex A). The response time is the time interval between the start of the temperature increase and the indication of an alarm from the supply and monitoring equipment.
NOTE 1: Linear extrapolation of the stabilized and the increasing temperature against time lines may be used to establish the effective start time of the temperature increase.
NOTE 2: Care should be taken not to subject detectors to a damaging thermal shock when transferring them to and from a stabilization or alarm temperature.
NOTE 3: Details and information concerning the design of the heat tunnel are given in annexes A and B.