what about this one ?

Is this a good substitute for a regular check valve ?

http://www.petersonvalve.com/backflow/photos.htm

It looks complicated and expensive... Plus that manhole for servicing... Ouch!
I didn't look far but what happens when the power goes out? It looks like it relies on power to operate.

I prefer inexpensive, simple, easy to service!

Good point about the power. I did not realize

it actually needed a electrical hookup to work! I thought some kind of battery operated thing...
I looked again- it does look like they want it hooked up to a power supply. I was wondering if anyone had used it at all.
Simple is good!

CONTROL PANEL

~ 22w x 18h x 11d (inches)
~ 120 Volts AC
~ 12 Volt rechargeable battery backup power supply
~ Weight: 55 pounds
~ Material: Painted Steel
~ Connections: .25 inch 150 PSI air hose hardwire
junction box

If you read the whole thing it said it comes with battery backup in case
of power failure.

I saw that, the problem is that this is going to be

installed in the yard, there is no electrical connection there. Since the battery is for backup only I assume that normal operation will require a line power source.

You way way overthinking this!

valve

From the picture it appears that the "valve" squeezes shut to seal. If so, it would only seal to uniformly shaped solids, not irregular stuff.

hj said:

From the picture it appears that the "valve" squeezes shut to seal. If so, it would only seal to uniformly shaped solids, not irregular stuff.

Click to expand...

Is this a classic case of "squeezing the crap out" ???

That's a pinch valve. It's an acceptable and preferred method sealing a sanitary line. The debris need not be uniform. It can seal around them or push them out of the way. We use them a lot in WWTPs.

Jason

Pan, it seems to me you are going at this backward. It may be you need a back flow preventer in your sewer line, but how do you know this? My advise at this point is to find a plumber in the Seattle area that does this type of work and have him evaluate your problem and make his recommendations as to what type of back flow preventer, if any, is needed. It just appears you are intent on buying what might be a very expensive device that you might not need, and if you do need something, don't force the plumber to use a product he may not feel is the best solution for your problem.

Ofcourse I am going to get a plumber...

I may be looking into this way more than you think is necessary, but I need to understand what is being done and if I am getting the best possible solution. You have helpoed a great deal.
As some of you have agreed before, just getting a plumber to give me his opinion did not necessarily yield good results. One of them even said the JR smith combination valve does not exist or he seemed confused about its purpose. I did read the specs and it clearly explains what it is for!
Do I need it ? Does it have its own cons ? It is entirely another matter- but I expect upfront explanation from them about their solution and when it does not happen, I come here.
Hence I am asking on this forum. I may still go with just a check valve, but I need to know what my options are. It may be a routine thing to see sewer backups for you guys, but it is not for me and I dont intend to if I can help it.

Thanks for all your help in this regard.

?s

Does your main building sewer back up into your basement during heavy
rains?
If so how often?
Have you had your main augered recently?
Thought about having your main cameraed?
These are things that determin the need for a back water valve.
There is probily more and when I think about it I will post back.

When they clean the sewers in the streets they use a jet machine that
uses extreamly high water pressure.It is possible that when they went by
your main it could have enough pressure to cause the condition you
described to me.