Important: Need Test Rig to Measure Volume of Air from High Point Vent Valves

Hi,

You don't mention the pressure of the medium that you are trying to remove the air from; but lets assume it is up to 10 Barg. Is there any water treatment or glycol in the media as this can cause problems at the point of pressure release i,e in the needle valve?

If there are no issues to resolve with the medium then:

Firstly you need to concentrate on getting a decent capacity of air bottle immediately beneath the automatic air eliminator, in this way you will overcome the problem of water and air being expelled simultaneously. it sounds as if there is very little separation between the flowing media and the air vent. There are a variety of AAVs with some heavy duty ones being better at dealing with sudden 'gouts' of air rather than a slow release of bubbles. But the air collection arrangement must be overcome before you attempt the next stage.

Secondly you can devise a very simple 'test rig' by using the discharged air to displace an equivalent volume of water from a vessel connected to thr AAV a bit like the old fashioned soda water bottles. Either collect the displaced water and measure it or if the problem is of a larger scale employ a 20 cubic ft vessel filled with water and fitted with a gauge glass; calibrate for volume to height change and mark the changes in meniscus level over time; This could easily be mounted on a trolley and moved into place when you wish to see what the air production rate is.

What ever method you adopt make sure there is no fluid transfer into the measuring system. Good luck.

Brilliant. You present a couple key ideas I had not thought of. Automatic Air Vents: Certain locations that are difficult to vent, such as when the vent is on a section of near-horizontal piping. When the vent is initially opened, air comes out followed by mostly water with some air. When the vent is reopened a few minutes later, a smaller amount air comes out followed by mostly water with a smaller amount of air. Eventually there will be mostly water with occasional bubbles. The desire is not only to measure the air volume but to restore the system to a filled condition. Removing large amounts of water is undesireable because it needs to be collected. The AAVs solve this problem by passing only air with minimal water.

The second brilliant idea was the soda bottle concept. We had thought of the idea of using an inverted bottle filled with water which would be heavy and difficult to refill. If I understand your idea correctly, we could use an upright plastic bottle filled to a high mark with a connection for the vent valve tubing and water output connection near the top of the bottle with an internal tube extending to the bottom. As long as the cap on the plastic bottle is air tight, this would work great.

The water displaced from the "soda bottle" would go to a collection tank. If the collection tank is slightly higher than the soda bottle, the system vent valve could be closed and a soda bottle vent valve could be opened to refill the soda bottle from the collection tank.

Thank you very much for your great ideas.

Hi,

Good to hear from you. The way you describe the air/water mixture is very typical situation and you will find that the circulating pump does an extremely good job at keeping the air or other disolved gas constantly in suspension. If you are still having problems with eliminating the air and you cannot readily form a decent sized vertical air bottle there are some products on the market which work on the principle of a cyclone and by causing a localised reduction in pressure within the unit they encourage the air to coalesce and come out of suspension whereupon an integral AAV discharges the vapour to atmosphere;and are very effective. They are intended for use in horizontal pipework so may well be the best solution for your application.You would have to cut the pipe and fit the device between flanges. One excellent product the ''Spira vent'' is manufactured by Spirax Sarco, there are others as well.

Let me know if there is any other help I can give you.