If anyone could direct me towards a product for purging gas from meters which have been removed, I would be grateful. Some of the meters contain diaphrams and will not naturally vent. Task is to ensure meter is safe prior to transporting and therefore gas free. Have done some online research but can only identify products that are very high spec for this task and are therefore very expensive.

Hilary, you are correct. Nitrogen can be used for the commissioning/ de-commissioning of gas central heating systems and other enclosed systems and vessels. Not sure for small pieces of kit it would be the answer. Nitrogen can also be a hazard by depleting oxygen from the atmosphere in an enclosed environment.