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Scuba Tech Tips: Regulator Venturi – Good or Bad?

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Alec Peirce explains how a Venture works and what it does for a regulator

By Alec Peirce, transcribed by DNN Staff

This particular tech tip in response to a question about ventures’. They are what helps make an airplane fly as well as assist in all kinds of other things. If you have shopped for a regulator in the last 15 years then you would note that ventures’ are also used in scuba regulators. 

So, what is a venture – is it good or bad and what does it do? 

First let me explain that regulators are very simple: there is a first stage which drops the pressure from 3,000psi to 150psi (I have gone over this before). There is a second stage that drops the pressure from 150psi to whatever the ambient water pressure is. There is a valve in here which is not simple but it is also not that complicated. The valve inside the second stage is really simple – a little lever you pull on and air comes out. When you suck on the mouthpiece, the diaphragm moves in and pushes the valve and you breath air. When you stop sucking, the diaphragm goes back out, the valve closes and the air stops.  Let me clarify – when I say simple I mean the principle is simple. In modern regulators, it is actually very sophisticated. Everything is geared and balanced. It all matches up so the air pressure and the flow match the spring pressure in the high-pressure seat and the flow of the air and the diaphragm is exactly the right distance – the levers are the right height and so much. Little things like the lever is held in place by a small screw. The lever moves up and down held by this screw as you suck in air – on the end of the lever is a little bend – manufacturers spent a lot of time and money figuring out how wide the bend should be and where it should be widest. So overall, today making regulators is very sophisticated.

Most regulator companies offer the same features. Every once in a while, a regulator comes along that is a little bit different – sometimes good sometimes not. Most manufacturers in their attempt to sell their brand they would try to add features to their regulators. Your job as a diver is to decide whether or not if those features are beneficial to you – do you need those features? A little while back we published a video on buying regulators – $300 or $800 and what’s the difference. They both let you suck air and while they do the same thing there are differences. Most of the differences are made up in features – some of which are beneficial while some are just nice. 

The venturi is a feature. Not necessary a benefit. I will explain what it does and you can decide if it is beneficial to you. I will open to second stage and show you inside. Inside you will find a diaphragm – in this case silicon. Push on this lever and air comes out and so forth. You use the flexible diaphragm to use the lever which causes it to push the lever. This particular regulator is a SCUBAPRO – excellent regulator. This one is particularly good for cold water and has adjustable breathing. This one also has a venturi. Let me show you. There is a small vane I am moving back and forth and it causes it to open or block the air coming into the mouth. The venture effect comes in here – the air comes out of the hose and air rushes out into your mouth – which is good. The venturi can be manually changed. The venturi when unblocked allows the air to rush into the mouthpiece and actually reduces the pressure on the diaphragm. The venture assist allows more air to flow. Is this really a benefit? One of the things that helps me suggest whether someone needs a venturi can be summed up like this: let’s say a lady, slim and fit walks in, she is less likely to need a venturi but then a big guy walks in, tall and maybe a little bit of a tummy on him, and perhaps he is not as fit as he should be – I would suggest a venturi. Why? He needs more air – he needs as much help to get air into him as possible. Or let’s say he has a strong current and needs to swim hard, he will need more air and the bigger the diver the more air is needed. The venturi is a great benefit in this particular case. 

The benefit is that it fills your lungs up if you need it. 

The disadvantage is that the air can be loud and make the water fly all over if you accidently drop the regulator in the water – but honestly it isn’t a disadvantage more of a nuisance. 

Now you know what a venturi looks like and how it works.  

Alec Peirce