The diaphragm water pump is not designed to pump air. If air is introduced into the system, the pumping action of the internal valve will suffer greatly. This is because air is not compressible, valve movement will be severely restricted.
An ineffective valve will not be able to generate enough pressure to overcome the 20 psi+ check valve, so the system will stall forever until the trapped air is removed.
If the check valve is placed at the end of a long hose, It will improve the chance of the pump recovering from trapped air situations. The stored water within the long hose will keep the outlet side of the internal valve wet, despite the presence of air, the valve will continue to work but at a lower efficiency. In time the trapped air will be expelled out of the system via the nozzle.
Although distancing the Check valve will help it is not the best solution. Here is a list of possible alternative solutions:
1. Reduce the check valve pressure down to about 10psi. (not suitable for DP).
2. Use a solenoid valve instead of a check valve. There is no pressure to overcome. Other advantages such as dribble free, instant on and instant off. (good for DP)
3. Pick a solenoid valve that is alcohol and water friendly.
4. Avoid putting on a low-cost solenoid valve.
5. Ensure the valve can withstand the pressure of the system.
I only recently noticed that this priming problem is more wide spread than I thought. I was aware of this until the topic is discussed here.
A solenoid valve or lower the CV's crack pressure will solve this. I am afraid it has to come from the horse's mouth. Only people would open their minds to advice from other sources.
There's been issues in the past where people got a bad taste with using solenoids. The solenoids being used in a W/A setup got globally scorned. The issue was not with the use of a solenoid but with the solenoid selected for the task and or possibly the install as well.
If a quality part is used (in this case the solenoid) and how well it fits into the overall system (how employed by the kit maker), you can get the expected reliability as well as getting the expected results in using it.
For users, what it really comes down to is first understanding how things actually work and then selecting the right parts to do the task as learned from a better understanding.
Now, in the case here it might be assumed that any use of a check valve in a W/A system is wrong, that's not the case . In actuality the issue is the incorrect application of a check valve.......................again, users need to get to the bottom of how things work and see things (if presented well enough to understand) in a manner that allows for them to select whats the best way.
A solenoid valve must have the following basic qualities for water/methanol injection.
1. A metal valve body is preferred over plastic. Metal has better dimensional stability over plastic. Suitable seals are essential also.
2. All solenoid valves produce heat when energized. Breakdowns are often caused by overheating, most probably with badly matched coil – wrong class of temperature rating is one of the causes. Low cost valves often have a lower class temperature rated copper winding.
3. Excess heat produced by the coil may be transferred to the metal valve casing and then finally passes on to the moving fluid through conduction. Plastic casing is not good in performing this task.
4. The pressure and orifice of the valve has to be matched with coil power. The higher the pressure and flow, the more power is needed. This applied to speed as well.
5. Low Grade stainless wetted internals cause corrosion. Quality valve use high grade stainless with good magnetic and low corrosion properties.
If the supplied solenoid valve has a high degree of failure rate, it is the supplier’s lack of knowledge to pick a good valve to sell, not the fault of the valve. Million of valves are used in millions of product.
The diaphragm water pump is not designed to pump air. If air is introduced into the system, the pumping action of the internal valve will suffer greatly. This is because air is not compressible, valve movement will be severely restricted.
Question:
The way i learned bro is air is compressible and a liquid is not. so this has me confused can you elaborate.
Answer:
In the pumps used for W/A injection air is not compressible. A pump designed for moving liquid can not also used for compressing air and vice versa.
The diaphragm water pump is not designed to pump air. If air is introduced into the system, the pumping action of the internal valve will suffer greatly. This is because air is not compressible, valve movement will be severely restricted.
Question:
The way i learned bro is air is compressible and a liquid is not. so this has me confused can you elaborate.
Answer:
In the pumps used for W/A injection air is not compressible. A pump designed for moving liquid can not also used for compressing air and vice versa.
I know you didn't mean to write that air is not compressible. Gasses are compressible, and that is the problem that keeps the pump from functioning properly until it's primed.
Sometimes I can not word things the way that would be best for understanding..............I struggle with writing things sometimes, sometimes its too long winded, laborious to read clearly and some times it assumes too much is already known and does not give enough.
I hope people see the issue trying to be conveyed though.
Well, I know one thing (and probably not much more than one! ), and that is that this thread illuminated an issue for me that I had never thought of. It had never occurred to me that a check valve could cause this priming issue, but it makes perfect sense.
so once i move my check valve from the trunk area and closer to the nozzle,will i have to do anything else other than reconnect the lines
If you want to keep the same setup in hardware, yes. Keep it simple for now and you will be happy.
The closer to the nozzle the better in that any thing in the line after the check valve will get sucked out under vacuum.......so if the line/distance between the nozzle and the check valve is shorter versus longer, thats good.
How close, needs to consider the realities of the install and room under the hood. No real need to put right at the nozzle but closer than farther is good.
how about "air is not compressible by this style of pump".
Yes that is a much better way in putting it.
Thing is though, if I go and edit the posts then may look like I'm hiding mistakes or something like that. I'm going to leave it.
Go back in this section and look for edited posts by particular users and you will get an idea to what i'm getting at. check the date of the posts and the date of the edit.......typically a truthful edit is only minutes from the org post. If theres a big disparity of time then be suspect of at least the post and maybe other posts.
If you want to keep the same setup in hardware, yes. Keep it simple for now and you will be happy.
The closer to the nozzle the better in that any thing in the line after the check valve will get sucked out under vacuum.......so if the line/distance between the nozzle and the check valve is shorter versus longer, thats good.
How close, needs to consider the realities of the install and room under the hood. No real need to put right at the nozzle but closer than farther is good.
my nozzle is mounted on my cold side pipe.and a 12ft hose runs from the nozzle to the trunk.than the hose connects to the checkvalve,and the checkvalve connects to the pump.i have plenty of room under the hood to mount the checkvalve,so its not a big deal
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Check valve installed directly at the pump outlet
), and that is that this thread illuminated an issue for me that I had never thought of. It had never occurred to me that a check valve could cause this priming issue, but it makes perfect sense.
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