Pump Shaft Seal

[fishytoo123]

Where can I find a pump shaft seal for approx 1/4" to 3/8" size shaft? I am trying to make a http://www.weatherson.com/sinusoidal_valve.htm
which I have most of the parts. I don't think it will look as nice, but as long as it doesn't leak.

[douggiestyle]

looking for one also. using 1 1/2" pvc inside a 2" pvc looking for 1/4" might be fine.

got a cool rotiserie motor. freebie.

its about 1.5 rpm. uses a geared down c frame motor. i think i can control the speed. haveent tried yet. need to check spacing on the 1 1/2" pipe.

[fishytoo123]

I have a piece of teflon or delrin rod that is 1.51" dia. Thinking that a piece of sch 40 1-1/2" at 1.60 id may work. Got some motors around but don't know the rpms of hand. any how the motors are cheap. I have a stainless pin from a old job we were doing for the one end of the cam. I like the design that the flow is straight, not a octopus type. Mcmaster has uv type pvc which is black for the outlets into the tank. Expensive pipe, spray painting the sch 40 is far cheaper. I need 3 outputs, based on the cam movement unless the holes were ported a lot there is going to be some backup pressure which if a holding tank is used coming off the chamber may produce a surge when the cam opens which could be a good thing. I just want to make sure it doesn't leak even if I use 2 seals a prime a center section between the seals with water to keep the end seal lubed just in case.

[BruiseAndy]

Can you bump shaft size up to 1/2"? If so finding them wouldn't be a problem. Maybe tear apart a broken or cheap external pump.

[fishytoo123]

I was thinking the same, but using pvc instead of stainless for the collar between the shaft and the motor. Then I could use a mcmaster part.

[BeanAnimal]

Good reading:
http://www.motionsystemdesign.com/Zone/Article/38353/Applying_shaft_seals_.aspx

Have used them:
http://www.anyseals.com/index.shtml

Good place for custom o-rings and seals (used them before)
http://www.americanseal.com/products/custom_orings_1.html

http://www.busakshamban.us/products.htm?pl=1&pf=9

http://www.esp-seals.com/

Sepco stuff is common and good:
http://www.sepcousa.com/products/mech_seals/index.html but may be a bit much!

A packing glan is also doable for low RPM low pressure:
http://www.industrialpacking.com/mechanical_packing.php is a material you could use

Or better yet somethign similar to an electrical nema packing.

Sealed bearings against a rubber or silicone seal... etc.

Just some thoughts...

[hesaias]

IMO< unless you can have a groove machined in your valve cap to put an o-ring in, a stuffing box will be the best bet. Any seal you use is gonna fail in that kind of service. Lip seals get stiff, teflon will wear the shaft, and a mechanical seal will not be able to deal with the particulate due to you not being able to set up a seal flush. All those spell disaster.

Just my .02. Any machine shop should be able to hook you up real cheap too.

[douggiestyle]

ive thought about a stuffing box. but they usual are slow leakers.
i posted in the diy om thread about using an old dishwasher pump seal. you get about 10 years of good unmaintained service in a caustic enviroment full of particulates.

[hesaias]

Actually, a stuffingbox is supposed to leak in order to cool the shaft, but since this is very , very low speed, you could probably tighten it down pretty good. Id still be scared of it though,

[BeanAnimal]

<a href=showthread.php?s=&postid=8889956#post8889956 target=_blank>Originally posted</a> by hesaias
IMO< unless you can have a groove machined in your valve cap to put an o-ring in, a stuffing box will be the best bet. Any seal you use is gonna fail in that kind of service. Lip seals get stiff, teflon will wear the shaft, and a mechanical seal will not be able to deal with the particulate due to you not being able to set up a seal flush. All those spell disaster.

Just my .02. Any machine shop should be able to hook you up real cheap too.

You said that better than I did..but I agree 100%

[BrainBandAid]

<a href=showthread.php?s=&postid=8889956#post8889956 target=_blank>Originally posted</a> by hesaias
IMO< unless you can have a groove machined in your valve cap to put an o-ring in, a stuffing box will be the best bet. Any seal you use is gonna fail in that kind of service. Lip seals get stiff, teflon will wear the shaft, and a mechanical seal will not be able to deal with the particulate due to you not being able to set up a seal flush. All those spell disaster.

Just my .02. Any machine shop should be able to hook you up real cheap too.

We use mechanical seals in sewage grinder pumps that are in service for many years (5+), without any kind of fresh water. You don't get much more particulate than raw sewage. We also use mechanical seals in the bigger sewage pumps, but they do have seal water.
As long as there is some cool water movement around the seal to prevent overheating and cracking it, a mechanical seal would be fine, IMO. Something this small and slow, I wouldn't worry about it.

And stuffing WILL wear the shaft. Just a matter of time. Our big pumps will wear through a hardened steel shaft sleeve in about 5-8 years, but that's with teflon packing, ~8 hour/day service, and fresh seal water. And they're designed to leak a little.

Just my 2 cents.

[fishytoo123]

I was thinking that the solid cam can be turned down on each end to .50 then countersink the cap end and expose the other end of the shaft through the seal. Machine a core to fit into a union that would accept the seal, then drill the end of the cam to accept the motor shaft and drill the side of the cam for a locking screw to hold the shaft. The material is teflon and I may not use any thrust washers. As far as a manifold to mate with the valve assy. I was going to use another 1-1/2 sch40 pvc with 1 port in and 3 ports out. I think a 1/2 rpm motor would work fine. I would be nice to have a dc gear driven motor and control the voltage for varying the speed, but I want to make this as cheap, but sturdy.

<a href=showthread.php?s=&postid=8891257#post8891257 target=_blank>Originally posted</a> by BrainBandAid
We use mechanical seals in sewage grinder pumps that are in service for many years (5+), without any kind of fresh water. You don't get much more particulate than raw sewage. We also use mechanical seals in the bigger sewage pumps, but they do have seal water.
As long as there is some cool water movement around the seal to prevent overheating and cracking it, a mechanical seal would be fine, IMO. Something this small and slow, I wouldn't worry about it.

And stuffing WILL wear the shaft. Just a matter of time. Our big pumps will wear through a hardened steel shaft sleeve in about 5-8 years, but that's with teflon packing, ~8 hour/day service, and fresh seal water. And they're designed to leak a little.

Just my 2 cents.

[fishytoo123]

I wonder what OM is using on there drive assy.?

<a href=showthread.php?s=&postid=8892161#post8892161 target=_blank>Originally posted</a> by fishytoo123
I was thinking that the solid cam can be turned down on each end to .50 then countersink the cap end and expose the other end of the shaft through the seal. Machine a core to fit into a union that would accept the seal, then drill the end of the cam to accept the motor shaft and drill the side of the cam for a locking screw to hold the shaft. The material is teflon and I may not use any thrust washers. As far as a manifold to mate with the valve assy. I was going to use another 1-1/2 sch40 pvc with 1 port in and 3 ports out. I think a 1/2 rpm motor would work fine. I would be nice to have a dc gear driven motor and control the voltage for varying the speed, but I want to make this as cheap, but sturdy.

[douggiestyle]

the stuffing box. similar to packing an old faucet. use teflon tape instead?

i need to look at this dishwasher seal more closely.

the thing with 1 1/2" pipe in 2" pipe is the tolerance is fairly large. 1/8"- 5/32" this would eliminate any tight machining tolerances. keeping it in the realm of hand tools and a drill press. so maybe a stuffing box might be more forgiving. would want to keep torque low on motor. otherwise im getting back into the $80 motor range.

[hesaias]

The problem with using a mechanical seal in this app is the speed of rotation. Its not turning a sufficent speed to work properly. Actually, with a stepper motor, its stopping and starting, which is very bad for mechanical seals.

I don't know the lower limits for speed in mechanical seals, but I will see if I can find out.

Think about a hydraulic valve. The deal with tremendous pressure, intermittant movement, and seall with 1 or 2 o-rings, fitted in a groove where the shaft penetrates the housing.

You could even do this by sandwiching thin pieces of acrylic, alternating larger OD and the right OD on the outside of the housing. Then just press the o-ring into the grooves created by the alternating ODs of the acrylic, and slip the shaft through, creating the seal.

[hesaias]

I did some thinkin about this and if you move the drive coupling outside the main housing you can lick this pretty easy by using 1/2-3/4" rubber lip seals inside the main housing cap where the drum shaft extends through, then couple the motor to the shaft with no worry about leaking through the housing into the motor. We used some automated valves on a big DI system here that used this type of sealing on water service that worked smashingly.

[fishytoo123]

Well I started to obtain parts. I found at mcmaster a 0.6 rpm 12 dc motor for 46.00, the a high pressure seal out of 316 SS for 27.00. Now I just need to turn the ends down on the drum/cam to .750 to ride in the 1-1/2 plug at one end of the pipe and machine a groove in to the plug at the other end for the seal. Line up 3 holes for the ports out and one for the port in. After mounting the hose barbs go back and ream out the cylinder with a 1-5/8 forstner bit. So I think the total cost including the material that I had on hand would be $100 bucks. I give it a half of a day in labor to build it, but I did have to have access to a lathe to turn the drum ends down to 3/4" other than that a drill press would work for the rest.