Air Button Help

[launboy]

Some of you may have seen my Spa build thread, most probably haven't, but quick summary... I bought a used portable hot tub, and am plumbing it in with the pool, like a spillover spa on an inground without the spillover. Everything has been going well for the most part until now.

Today I tested my air buttons and ran into a major issue. My equipment is about ~35ft from the spa and where I was planning to put the air buttons to control the two pumps, blower, and light. The problem is, my buttons don't create enough pressure over the 40ft of tubing to actuate the switches. If I blow into the tube, I can actuate the switches, but the buttons just can't do it.

I COULD just move the buttons closer to the pumps and mount them to the wall of the shed. This would give them a 15 ft. run, but then you have to get out of the spa to use them and I'd rather not do that. The only other solution I came up with was to put an aux. compressed air tanks under the spa shell and use a momentary Pneumatic switch, like this one Click Here from McMaster-Carr.

Any other Ideas???

Thanks,
Adam

 

[spishex]

I don't think that switch would work since the pressure wouldn't be relieved after the switch is released. The air switches at the pack required the internal diaphragm be pushed up and then let back down again, basically like the clicker on a pen.

Maybe you could try emailing somebody who has a few in stock like this guy and ask him to test a few over that long of a run. I bet all you need is a slightly stouter button.

Are you using the buttons on the topside control that came with your pack or did you get different ones?

 

[HarryH3]

What kind of tubing are you using? A soft tube is more likely to expand slightly, absorbing much of the pressure pulse as it does so. Also, the larger the diameter of the tube, the more air that has to be compressed to move the pulse to the other end. You need a very rigid tube, with as small a diameter as possible to pass the pressure pulse to the switch.

 

[cobra46]

The other two solutions will help but it depends on the pressure requirements of the switch as to whether they will work or not. A small diameter tube can have a very difficult time transmitting the pressure over long distances. I doubt if the expansion of the tube is much of an issue at the very small pressures you are working at.

Your idea will work it you locate a valve that has three ports NC, NO and COM. This will allow the pressure in the switch side of the line to bleed off to atmosphere after you release the button. Try Festo or SMC. I use their products quite frequently in my line of work.

Good luck and let us know what you come up with.

 

[launboy]

I tried 3 different types of air buttons. The ones that are attached to the temp. control(for spa pack) the one that came with the tub jet pump, and another one that came with the hot tub. They all click the switches at with short runs(5 ft).

I thought tubing stretch might be an issue so I bought 1/8" black tubing used for drip irrigation. It's like black poly pipe(that may be what it is).

Didn't think about the switch return issue. So, when I went to test that part out I found out the all switches do return. The one on the tub jet pump isn't sealed and the pressure leaks out almost instantly, but the ones on the spa pack lose pressure rather slowly.

Then I realized two of my four buttons are built into the topside control panel that came with the hot tub. Now I'm thinking I might mound the topside control in the wall of my shed(about 8 ft. from the hot tub) and put the two extra buttons there as well. This poses two problems... First, the six wire plug for it is only 4 ft. long. I think this could be easily solved by cutting it in half and using two cut extension cords(or 6 wires in a flex conduit) to extend it.

Thanks,
Adam

 

[launboy]

Have to add to that last post. So, even the shorter run didn't get the buttons to work. That was using the black poly. So, I figured, what the heck, and connected all of the short pieces of clear tubing that came with the pumps together(which came out about 3ft shorter then the black poly going to the shed wall) and guess what? It WORKED!

So then I looked at the package for the black poly and saw that it wasn't 1/8" like I thought, it's actually 1/4" pipe. That wider diameter explains why I couldn't get enough pressure to actuate the switches. Now I just have to find somewhere to get 150 ft. of the stuff for CHEAP.

Adam