Thread: HOme made manometer

That would be correct. But I do not think you want to leave it connected all the time. The sensor that is in the air stream will eventually fail.

The water may move a bit when the plug is added but also when in use the plug will stop air entering as the water is pulled down and start to create a vacuum. This will cause the measurement to be significantly low. It needs some opening even if the opening is smaller than the tube diameter. As long as the tube diameter is consistent through the reading range then it will be accurate.
Putting plugs in both ends of the tube when not in use would stop evaporation and would be a good idea if you use it often. I get the impression that you have it hooked up for continuous use and wonder why. Most people would only use them for spot checks like leak testing.

Use of tubing to suit the 4mm drip retic fittings means the small taps available for this tubing can be used on both sides of the "U-tube" tp prevent water evaporation when not in use.

Continuous use could be used to assess how fast DC filters are clogging up.

What sensor are you talking about? This is a rubber tube that has no propensity to fail.

Confused. One end goes into an opening cut into the cyclone. I would have thought that would have provided a breathing hole.

Are you an engineer? This makes no sense to me. I'm not an engineer. I dont know what your talking about but I would like to. It may be helpful.

Oops, I've been using the wrong "reply" button.

Here's what I mean.

The "X's" are small drip irrigation taps.
When you want to make a measurement the taps are open - otherwise close them and you wont lose any water to evaporation.

I've coloured the water red because it's the easier to see if some food dye is added to it.
Screen Shot 2018-12-27 at 7.03.54 am.png

To use the black/blue drip irrigation taps the tube has to have ~4m ID , or if you use other tubing use suitable adapters.

Everything has to be well sealed so I drill and tap a 4mm thread at the pressure sensing point and used a 4mm threaded black drip irrigation coupler and add some thread locker before threading the coupler into the sensing point. To the coupler I attach 4mm black drip irrigation tubing down to a tap just above the manometer. On the other side of the tap I use 4mm ID PVC tubing for the manometer.

Thank you for the art work. In my venue, it will be simpler to maybe throw a bolt on top of the tube that slows evaporation and just add water from time to time. I have a water tap in my shop. Also, while I was experimenting, I added a screw through the tube for draining when there's too much water.

Originally Posted by sussertown

Thank you for the art work. In my venue, it will be simpler to maybe throw a bolt on top of the tube that slows evaporation and just add water from time to time. I have a water tap in my shop. Also, while I was experimenting, I added a screw through the tube for draining when there's too much water.

Most evaporation actually takes place from the side connected to the sensing point because that is the side that is under vacuum.

Or make one with a large reservoir, this crude one has been permanently connected for years and only dropped the thickness of a pencil line in that time.