EN 308-1997 pdf download.Heat exchangers Test procedures for establishing performance of air to air and flue gases heat recovery devices.
4.9 pressure
Relative pressinm are measured as difference to the atnrnspherw preure. t’nk’ss otherwise specified the term pressure is used for relative pressure.
NOTE 1. Absolute pressure is used for air and fluids properties <‘aletilation
NOTE 2. Pressure drop is the pressure difference along a cin’uit.
5 General requirements
The European Standards EN 306, prEN 306, prEN 307 shall apply where appropriate and not otherwise stated in tire following clauses.
5.1 Heat recovery device
The heat recovery derice to be tested shall be installed in a test rig in accordance with the manufaci urer’s pul)llshe(l in.stnwtions.
5.2 External leakage
The air tightness is established by the external leakage at positive and negative pressures of 401) Pa. The external leakage shall be dctenuined using tire test arrangement as described in 6.1, with mean positive and negative presstires of 4(s) Pa relative to ambient (‘ondition On supply aIr(i exhaust air sides respectively. The nwasured mass flow rates qmcp an(l qnien. the external leakage flow rates, shall be recorded in the test report as a percentage of the nominal air flow 100 % Air density during measurements shall be between 1,1(3 kg.m’’ and 1,24 kg•nr outside this range the ineasureincirts taken shall be corrected to reference conditions.
if (he recovery device is constnic’ted without any common wall between the supply and exhaust air SHies, the external leakage (Ul be detennined for the supply and exhaust air exchangers separately at 400 Pa positive and/or negative pressure and stunmated to indicate the external leakage for the whole recovery (levice.
For those recovery devices which are intended for use in systems with static pressures of 250 Pa or below, the external leakage may be determined at 250 Pa instead of 400 Pa. This fact shall cleariy be stated in the ttst report.
5,3 Internal exhaust air leakage
The air leakage between the two sides in a recovery device is represented by the exhaust air leakage, mass flOw rate ‘lmil into the supply air side with a nsiire of 250 Pa in the exhaust side and 0 Pa in the supply-air side, using the test arrangement described in 6.2. Air den.siy dining the measurements shall be between 1,16 kg.rn and 1,24 kg nr3, outside this range the nwasurentents taken shall be corrected to reference (‘Ohl(lit lOBS.
NOTE 1, Measurenwnts taken with 0 Pa prisaun on 11w supply air Side givi. iiw internal exhaust air leakage only. exeluilitig any casing l(’4ikiii.
The internal leakage shaft be detennined for recovery devices belonging to categories I and Ha and shall be recorded in the test report as a percentage of the nominal air flow (Qm!Qnin) However, the internal leakage test is not applicable for category II devices without any common wall between the supply and exhaust air sides.
For those recovery devices of category I, which are designed for use in systems with static pressures of 250 Pa or below, the internal exhaust air leakage may be detemiined at a pressure of only 100 Pa on the exhaust air side. This fact shall clearly be stated in the test report.
NOTE 2. The internal exhaust air leakage ol these recowiy devtees depends on their design uid co.astruutlon. As these caui viuy and the design pressures on the two air sides an normally known It is hruesasiy to ilcerlaw the drgriw of ak-loss.
NOTE 3. The tracer gas ledunque can also be applied ror measunng the Intertud exhaust air leakage (or category I and lii 5011W cast-s for calegoiy IL
Recovery devices for category 111 (for example, rotatng regenerators) are known to be subject to leakage and the leakage flow rate depends on the effectiveness of the seals. Therefore, these devices are usually installed with overpressure on the supply air side and data for leakage of supply air into the exhaust air side is nornially given by the manufacturer. Even with this pressure requirement sonic small amount of internal leakage (of exhaust air Into the supply air side) will be obtained by the rotation of the rotor, the so called carry-over. However, this carry-over cannot be
eertainetl with the above desenlw(l test method for internal leakage.EN 308-1997 pdf download.