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E-mail: ductless@escoglobal.com Website:
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APPENDIX
SECTION B: CALCULATION
Minimum face velocity
Record which of a, b, c, d, e, f, g, h, i is the smallest
Is the value above or below 0.3 ms
-1
? If it is below, the fume cupboard fails.
Variation
Add a, b, c, d, e, f, g, h, i, and divide by 9 to get the average.
Find the biggest and smallest value of a, b, c, d, e, f, g, h, i.
Calculation: Biggest minus average. Divide the answer by average and multiply by 100 to obtain the
lower percentage variation.
Is each of these less than 30%? If not, the fume cupboard does not meet the recommendation and, if a
new installation, should not be accepted.
The variation in favourable conditions should be below +/- 20%. However, because it is difficult to find
ideal sites in many laboratories, +/- 30% has been stipulated.
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