ASHRAE110-1995 (ANSI approved) is one of the most challenging standards in the world that tests the containment efficiency of a fume hood. The efficiency is derived from the fume hood's ability to contain the released challenge gas under normal operation. The ASHRAE110-1995 test facility at Esco is constructed based on recommendation given by Invent-UK, a third party organisation that certifies fume hoods. There are there parts to ASHRAE 110-1995 standard; the flow visualisation, the face velocity uniformity test, and the SF6 containment test.
Face Velocity Test
Tracer Gas Containment
The flow visualisation helps to identify potential locations within the enclosure and at the sash opening where eddy currents and turbulence are likely to form. Smoke tubes and candles are used to map out the flow pattern which then enables us to improve on the flow dynamics generated by our fume hoods. The face velocity uniformity test evaluates the uniformity of the inflow velocity at various points across the sash opening while the final part, i.e. the SF6 containment test, evaluates the containment efficiency. A very sensitive SF6 particle detector, capable of reading as low as 0.01ppm, is used in the detection of leaked SF6 during the containment test.
The derived performance as determined by the smoke visualisation test and the face velocity uniformity measurement provides a valuable indicator to the containment property of the fume hood. The SF6 containment test provides the ultimate proof in establishing this sequence. If the results of the smoke test and the face velocity test are good, then the containment capability of a fume hood is considered good.
For further information on the test method and observed results, please download detailed report.
Here in Esco, we are capable of conducting the complete ASHRAE110-1995 test in our laboratory.
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The EN14175 comprises of a series of containment tests besides the normal face velocity tests. The containment tests include, the Inner Measurement Plane Tests, Outer Measurement Plane Tests and the Robustness of Containment Test. The challenge gas which is released into the fume hood is 10% SF6 and 90% N2. A set of sampling probes is positioned at various predetermined locations to monitor SF6 escaping from the hood.
For the inner and outer measurement plane tests, the detector probe set is moved accross the sash opening at various heights and sash positions, thereby describing the overall containment efficiency of the fumehood under normal operations. In the case of the robustness test, a vertical plank mounted perpendicular to the sash plane is made to run to and fro accross the sash opening at a fixed speed. This disturbs the inflow and gives an opportunity for the SF6 to escape. A reliable fumehood ensures that at that level of disturbance, the fume hood is still able to quarantine the released SF6.
For conformity evaluation, a type test is carried out on one of Esco's EFH units fresh off the production line. And thanks to Esco's design, the EFH passed the performance requirements of EN14175.
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