Sampling

Taking A Sample: USING GRESHAM GAS/AIR SAMPLING EQUIPMENT

All procedures in operation on the site relevant to monitoring and control must be adhered to. If sampling is to take place in a confined space, work systems as defined in HSE Guidance Note GS5 "Entry into confined spaces" must be followed.

Sampling with the Gresham Hand Pump, Single or Double Headed Sample Cylinders and Filling Indicator (optional).

1) Remove Dust Cap from Cylinder Head.

3) Plug the Sample Cylinder into the Bayonet Adaptor on the Pump. The Filling Indicator (if being used) is fitted between the Pump and the Sample Cylinder.

4) The Cylinder should now be purged by pumping up to pressure several times and releasing the contents of the cylinder as in 2 above. With Double Ended Cylinders the Purging Attachment can be used. The Attachment is fitted to the "free" end of the cylinder and the pump "pumped" several times to enable sample to flow through to atmosphere. The Attachment is removed before the sample is taken.

5) The sample is now collected by "Pumping" the Pump until the required pressure of sample is obtained within the Sample Cylinder. This can be monitored by using the Filling Indicator or by counting the number of Double Strokes, (Push/Pull), of the Pump that have been made. As a guide the table below shows the number of Double Strokes required to obtain a sample of 14 bar (200 psi) in the different size Sample Cylinders available. THE PRESSURE MUST NOT EXCEED 17bar (250 psi).

Cyl Capacity (ml)	15ml	30ml	55ml	70ml	110ml
No Push Pull Strokes	9	16	24	33	43

When using the Filling Indicator the number of strokes shown above will register the gauge approximately mid-way in the green section.

6) When the sample has been taken the Sample Cylinder is unplugged from the Pump and the Dust Cap replaced. The Sample Cylinder now contains the sample ready for analysis.

7) In the laboratory the Sample is released from the Cylinder using a Cylinder Testing Unit.