Leakage rate method

ASTM E779-87. 1987 Standard Method for Determining Air Leakage Rate by Fan Pressurization.. American Society for Testing and Materials, Philadelphia. 

When using the positive pressure method it is sometimes either impractical or in fact impossible to measure the leakage rate directly while it could certainly be sensed in an envelope which encloses the test specimen. The measurement can be made by connecting that envelope to the leak detector or by accumulation (increasing the concentration) of the test gas inside the envelope. The bombing test is a special version of the accumulation test (see Section 5.7.4). In the so-called sniffer technique, another variation of the of the positive pressure technique, the (test) gas... 

All ductwork should be sealed in accordance with SMACNA Class A rating, which requires all seams, joints, fasteners, penetrations, and connections to be sealed. Sealant should be FDA acceptable for the application, and nonhydrocarbon based. Leakage rates as low as 1% total airflow are not uncommon. All ducts passing through a clean room wall or floor should be provided with stainless steel sheet metal collars and sealed at the opening. Details of sealing methods should be provided on the design documents. 

UL 555S Standard for Leakage Rated Dampers for Use in Smoke Control Systems UL 723 Standard for Test for Surface Burning Characteristics of Building Materials UL 790 Standard for Standard Test Methods for Fire Tests of Roof Coverings (2004)... 

Air leakage measurements use a system of controlled negative pressure in which air is pumped out of the respirator to create a fixed negative pressure (usually 1 in water gauge) and the airflow need to maintain this pressure is measured. The airflow is taken as the same as the leakage rate into the respirator. The method requires wearers to hold their breath and the filter canister to be blanked off (otherwise, air will leak through the filter). 

Methods must be devised for assessing carbon dioxide losses during transfer operations and also the leakage rates from each type of store. Several techniques are available or under development but these vary in applicability, site specificity and detection limits. The formulation of protocols for monitoring the hazards associated with carbon dioxide capture and transfer does not appear to present fundamentally new challenges, as similar protocols are part of standard environmental health and safety practices for toxic gases. 

Air-leakage rate based on the system volume method is given by Sieder et al. (2009), as shown in Equation (11.1),... 

The basic method of calculation therefore involves the knowledge of two parameters the radioactive concentration of the contents of the package, and its volumetric leakage rate. The product of these two parameters should be less than the maximum permitted leakage rate expressed as a fraction of Aj per unit time. 

The changes in -ater le e in three pressurized tanks (A, BandC) is used for detecting the leakage rate. This method is applicable for the steady operation state. The operation practice indicates the normal leakage rate is about 1 1/hr. 

Various methods have been proposed for estimating air-leakage rates ... 

Leakage rates can be estimated by assigning nominal leakage rates to system components. This method can be cumbersome and is not readily adapted to predict leaks resulting from fabrication and assembly errors. 

Once these factors have been determined, the remaining problem is to compute L and r since these quantities establish the neutron-leakage rates for the finite system. A first approximation to L has already been given, and a few remarks have been made about corrections for directional effects. Some methods have been developed for including anisotropic effects in the computation of the migration area, and these are reported in a subsequent section. 

Method Test fluid Threshold leakage rate (mbar 1 s ) System pressure Leak localisation Quantitative leakage rate statement... 

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