Charcoal Tubes

49

The standard NIOSH charcoal tube is the standard method used generally for organic vapors. Suitable for most general aromatic hydrocarbons and alcohols. Not suitable for aldehydes, nitro compounds or carboxylic acids.

Chromosorb Tubes

Available in a range of porous polymer sorbents for more complex compound monitoring

Poropak Tubes

Available in a range of porous polymer sorbents for more complex compound monitoring.

Tenax Tubes

Available in a range of porous polymer sorbents for more complex compound monitoring.

Silica Gel Tubes

50

Silica gel tubes are used as the adsorbent material for polar hydrocarbons, low molecular weight mercaptans, methanol, amines, and inorganic acids. Some specially reagent treated tubes are also used, eg. 2, 4-dinitrophenylhydrazine for aldehyde sampling, sulfuric acid treated for ammonia.

Sampling Pump Accessories for Gas and Vapor

51

For gas and vapor sampling a volume of air is adsorbed onto a sampling medium held in glass tubes. To enable a high flow pump to operate at suitably lower rates a low flow adaptor must be used. The low flow adaptor is used to reduce the flow rate of standard air sampling pumps from the range 1000 to 4000 ml per minute to a much lower rate from 5 to 750 ml per minute. The sampling pump is set within its normal flow range, typically 1.5 l/m and then the low flow adaptor uses an in-line constant pressure controller and flow adjustments are made to a “controlled leak” screw that sets the actual flow rate for the tube in use. The actual flow rate must be monitored and set using an external flow calibrator such as the Defender 510 or 520 series unit.