Dangers of airleaks

[JohnA]

I've just realised that my pump was very noisy because there were airleaks in the water 'intake' side of the system.
They looked neat, tight and dry, but they were not.
After a chat with Richard Lamb (Mr Aquamist in the UK) I realised that the pump should NOT be as loud as it was, and air bubbles should NOT be visible on the high-pressure line.
The water line is now fixed, and the system works right as rain

So beware - there could be air leaks and you wouldn't see anything wet or funny!

[Brad]

John, where is your pump mounted in relation to the bottom of you water tank. It is always best if the pump is below the water source.

[JohnA]

John, where is your pump mounted in relation to the bottom of you water tank. It is always best if the pump is below the water source.
I know, but my water source is low (low part of the front wing) and there's no space for relocation.
But I've also placed my pump rather low, on the battery tray next to it, so the height difference between the pump and the water level is only a few inches max. During my 'leak test' period, the water level was higher than the pump.

These air leaks were very sneaky, the only indication that they happen is the extra noise from the pump and the bubbles in the high-pressure hose.

[Brad]

John, Where was the air leak? I have had my most trouble at the filter. When forced to mount the pump higher than the bottom of the water soruce I try and make sure the filter is a low a the water inlet.

[JScoob]

How often have you gotten air bubbles?

I'm pretty sure I'm leak free, but the other day, I got a random detonation event out of nowhere. I think it may have been an air bubble. I'm concerned that any air bubble happen at all now. Is there a way to 100% avoid it?

My pump sits vertically, with the inlet pointing up. The pump is at the bottom half of the tank. The filter is at the top of the tank.

So something like this:


_{filter}________ <--- water flow
| |
_______| ----------
| | |
| | tank |
[pump ] | |
| -----------
|
---------> water flow

[Brad]

With the installation of the filter above the water level, the connections a the filter provide a very good place for air to be drawn in. when the pump is trying to pull in water it can pull in air at the inline filter clam. If you were have the tank taped near the bottom of the tank and the filter placed so that water level was always above the filter the change of drawing air is far less. I have been involed in hundreds of installations, most over the phone but I have learnd from every one elses mistakes and my own.
The other problem that comes up is the shap of the tank compared to how the car is used. Some use very nice tanks but have too large of bottom surface. When cornering, braking or acclerating hard the pickup comes uncovered and the system gets and air bubble. This is not too harmful on a 1s type system as it will purge it self very well but it is a 2c, 2d or 2s type system the pump gets an air bubble traped in the pump. The system has to be blead to get the bubble out.
A tank that is vertical in nature works the best. If you consider cornering forces and braking forces of 1g and over you can see how a tank pickup can be uncovered. If you have a large bottomed tank a small tank mounted lower as a reserve for high g conditions can be useful.

[JScoob]

Ok, I will move my tank tap from the top to the bottom. This should minimize the amount of water having to flow against gravity, as well as keep the filter level with the bottom of the tank.

I guess my real question is whether the aquamist pump can accidentally insert air pockets, assuming perfect water input and perfectly sealed tubing all the way to the nozzle. If I do everything right and the pump still can add air pockets, then my efforts really don't matter - in the end I'll heavily detonate in those instances.

I don't quite see how the 1S is any better at purging air pockets. Is there something about it I'm not aware of? I thought it was just the most basic WI kit?

[Brad]

When all is setup correctly I have not see air enter the system. About the only place it could be generated is if the pump got hot enough to boil the water in it. This would cure it's self when cooled down.
The 1s only has to push past boost pressue. On the 2c,2d and 2s we maintain 7bar in the line. So lets say the pump is running the pickup get uncovered and air gets into the system. The air will compress and not pass out of the pump. The pump will continue to run but it never clears it self because of the 5bar pressure line pressure. If the pump had a much greater volume for each stroke it might.
On most occasions the boost incountered by a 1s is only about 1 bar.
If the pump is accidentlly inserting air the pump would have to be defective.

[Forum Admin]

I think the Aquamist pump has a temperature cut that would occur before water would boil also with the water passing through it the pump should be kept cool under most intended uses. The only exception is if the pump is located in a hot spot and the heat sink absorbs instaead of dissipates heat.

With the filter as the highest point in one of my systems it can get air initially trapped in it but this should clear once primed. I also had a leak at that filter connection that was pulling air in. The pump reacted badly enough that it was noticable and corrected quickly.

A sealed system with any pump appropriate for water injection should keep air out of the system and not cause any problems.

[JScoob]

The air will compress and not pass out of the pump. The pump will continue to run but it never clears it self because of the 5bar pressure line pressure. If the pump had a much greater volume for each stroke it might.

If this were the case, water is actually not moving and just sitting with 5bars of pressure in the lines right? Wouldn't that be detected as a blocked jet? I guess as long as I maintain my tank nearly full, the chances of this happening are at a minimum.

I also had a leak at that filter connection that was pulling air in. The pump reacted badly enough that it was noticable and corrected quickly.

This may be a dumb question, but why would a leak cause an air bubble in the line? Wouldn't the 5-7 bars of water pressure push water out, and not let air in? The worst thing that should happen is that I have less pressure in the water line, but I don't see how an air bubble could sneak itself in there since the pressure gradient flows from inside to outside.

[Brad]

Depending on whick detection system you would be using. Every thing but the DD2 detects blocked nozzle by pump running. This type of detection is only on the 2d and 2s systems.
As for the air leak causing a bubble, the air leak is on the pull side of the pump. The inlet side of the pump creates a vacuum. A small leak and develop at the filter connection that is small enough to let air in but water will not flow out. The 5 bar in the line is being held but the pump output check valve. It is the air getting traped in the pump or pump feed line that causes the problems.

[JScoob]

Gotcha.

Most of my plumbing is on the outlet side of the pump - so I was focused there as possible leak points.

[JohnA]

John, Where was the air leak?....
I had two airleaks, both on the low-pressure hoses.
One was the connection to the pump inlet, the other was the exit from the filter.
The leaks were obvious when I connected another tank of water high up (instead of the pump) so water was leaking everywhere. In the normal setup everything was nice, tight and dry (that's why it could be sneaky)

The telltale is the pump being noisy and the bubbles on the high pressure line.

If you want to see my setup, do a search on my website for 'methanol'

[janis]

Holy cow,

I just checked out the max-boost.co.uk site

What a whealth of information. Great site!

Janis

[JohnA]

Thanks :lol: