Specifications - Gilberts (Blackpool)

Ministry of Justice Specification(Type GPS)3mm holes - Staggered 5mm pitch.Home Office Specification for Police applications(Type GPP)2mm holes - Triangular 4mm pitch.PerformanceDataThe performance data nomogramsthat follow are related to isothermalconditions. They can be applied foreither supply or extract selectionpurposes and are intended to be anaid to the design engineer.References used:PRESSURE: All pressures are inPa (N/m 2 ).SOUND: measured in average dbalevel.THROWS: All horizontal throws arefor a distance measuredin metres and correspondto a terminal velocity of0.25m/s.SelectionProceedureHaving established the position where the supplyterminal can be situated measure the acceptable throwdistance. It is better to position the supply Grille at highlevel in a side wall with the discharge of air over theceiling and extract at a lower level. Knowing the volumeand throw for each Grille then use the nomogram tocheck:A) Size as selected to give required throw of air.B) Noise level from performance data to ensure it meetswith required specifications.C)Determine the static pressure drop fromperformance data.Example (Type GPS):Volume required 0.06m 3 /S.Throw 5/6 metres.Max Sound Level 35 dba.From Chart selection of 300 x 300 Grille gives thefollowing data:-Throw - 6 metresSound Level - 24 dbaPressure Drop - 8 paSelection of extract Grilles are generally based uponacceptable pressure drops and noiselevels3