High Efficiency Particulate Air (HEPA) filters are manufactured and individually shop tested to remove >99.97% of the particles with a mean diameter of 0.3 microns from an air stream at rated flow and are evaluated in pre approved test facility before acceptance. After installation, these filters must be again evaluated. This second phase of evaluation is known as insitu testing. This testing is used to detect leaks in HEPA filter installations in their operational conditions, which is intended to test the filters, seals, housing and terminal duct work and, in addition to filter integrity, it also ensures that all air entering the controlled environment passes through HEPA filtration system. 

Performance of HEPA filter installation is evaluated by measuring the aerosol concentration in a sample taken from the upstream side of the filtration system and comparing it with a similar measurement of aerosol concentration in a sample taken from downstream side of the filtration system. 

All the testing equipments like aerosol generator and particle counter are available in local market. 

Three trained personnel having Diploma in Engg./Degree in Science would be adequate to perform this testing.

INTRODUCTION

High Efficiency Particulate Air (HEPA) filters are manufactured and individually shop tested to remove >99.97% of the particles with a mean diameter of 0.3 microns from an air stream at rated flow and are evaluated in pre approved test facility before acceptance. After installation, these filters must be again evaluated. This second phase of evaluation is known as insitu testing. This testing is used to detect leaks in HEPA filter installations in their operational conditions, which is intended to test the filters, seals, housing and terminal duct work and, in addition to filter integrity it also ensures that all air entering the controlled environment passes through HEPA filtration system.

ADVANTAGES

Insitu testing of HEPA filter installations, employing pretested and undamaged HEPA filters, are mainly concerned with assessment of leakages, through the paths other than the filter element such as insufficient gasket compression, defective filter mounting frames, cracks on masonry works etc. These defects/deficiencies in installations are noticed and corrected with the help of inistu testing.

APPLICATIONS

This testing is used to detect leaks in HEPA filter installations in their operational conditions, which is intended to test the filters, seals, housing and terminal duct work and, in addition to filter integrity it also ensures that all air entering the controlled environment passes through HEPA filtration system.

PRINCIPLE OF INSITU TESTING

Performance of HEPA filter installation is evaluated by measuring the aerosol concentration in a sample taken from the upstream side of the filtration system and comparing the same with a similar measurement of aerosol concentration in a sample taken from downstream side of the filtration system. Usually a suitable aerosol is generated and injected in the upstream side of the filtration system. The insitu testing are mainly concerned with searching for pin holes, leakages or bypasses in the system, which are usually less size selective than for an intact filter element or filter medium.

EQUIPMENTS :

All the testing equipments like aerosol generator and particle counter are available in local market.

INFRASTRUCTURE :

Apart from experienced and trained personnel, an investment of about ` 8 Lakhs is required.

MANPOWER :

Three trained personnel having Diploma in Engg. /Degree in Science would be adequate to perform this testing.