sequence snapper and super squirt OM questions

[EnderG60]

ok im trying to layout a closed loop system for a client and need some info.

we are planning to use a snapper pump with a 4 way OM super squirt. but we have a size restriction on a hole in the wall to shove all the pipes through. The tank is a 92g corner tank.

Now the snapper has a 2" inlet and 1.5" outlet. The OM only has a 1" inlet, so would be be a problem to run 1" all the way from the pump to the OM or have 1.5" out of the pump for a foot or so then reduce it to 1" for another foot is before the OM?

OR if 1.5" must be used right up to the OM could we reduce the inlet pipe to 1.5". this would be a better idea if its doable since I need to hide all the pipes and 2" is pretty big.

Also for the intake pipe, should I use a long reverse spraybar type intake or just a strainer at the end of the pipe?, Or does the overflow box have enough teeth to allow me to put the intake inside the box?

[jessezm]

You're okay to reduce from 2" to 1.5" on the intake, but on the output from 1.5" to 1", I would give sequence a call... I called for the very same reason, and they said that from 2" to 1.5" you won't see too much of a difference. However, reducing from 1.5" to 1" does cause a lot more restriction. But in your case, since it's on the output side, I think it would be okay since it shouldn't cavitate from extra pressure on that side. The pump is going to work harder, though. For what you're trying to do, you are much better off reducing the 2" pipe, but you might be able to get away with both. The 1.5" bulkhead is also a lot cheaper than the 2" bulkhead, so that's another reason to go that route.

For the strainer, definitely do not install it in the overflow box, it will be harder to balance the flow, even if the box can handle it (not worth the risk, in my opinion). For the in-tank strainer, use a 1.5" Tee with one strainer facing up and one sideways (if you're coming up through the bottom of the tank. You can get black PVC for this from Savco so it's less obvious. Where is your install? if it's close to me, I could come check it out.

[EnderG60]

all of this piping will be over the sides of the tank since its not drilled for anything but the overflow kit.

Well in order to make it fit through the hole I either have to reduce the intake to 1.5"...or reduce the oulet to 1"(which i figured would be ok since the OM is all 1" anyway, but ill ask OM/sequence about that) If i can do a 1.5" inlet and 1" outlet all my problems are sloved.

as for the intake, would two strainers and a T be a better idea then one strainer and drilling a bunch of holes or cutting some slots in the pipe? Just to reduce the amout of space it takes up. Im planning on putting some egg crate around it so it can be easily removed and cleaned if it must be in the tank.

and he is in kennesaw

[jessezm]

Do ask, but I'm pretty sure reducing both sides by .5" would work.

As for the strainers, I'm not really sure from personal experience which way would work better. Just do whatever ends up being least restrictive but gives you protection against incoming snails and the like. I'm going to be trying the T method for my closed loop intake as soon as I get my tank set up. I have a Dart and a standard OM 4-way to plumb. Unfortunately, Kennesaw is a bit out of my way, otherwise I'd be happy to come check it out (though it sounds like you know what you're doing).

[xchrisjb]

Having a 1" pipe on the pump output isn't going to be a problem, other than the reduction in flow.

I'd be sure to have two inlets, minimum of 1" dia, within the tank that are then T'd together before the pump, and I'd personally have them meet at least 12" before the pump inlet. And as was said, having the input pipe reduced down to 1.5" is fine too.

As far as covers/strainers for the inlets, I think that's as much a function of what's being kept in the tank as anything else. I would still have a pipe with a lot of small holes drilled in it (making sure total area of holes is > than intake pipe area) on each of the two inlets. Make them out of black or grey pvc to help hide them in the tank.

[stereomandan]

My 2" strainer works great for my Snapper.

Two 1" inlets is a BIG reduction on the inlet side. 2" PVC had 3.14 square inches of pipe area and two 1" PVC pipes only have 1.57 square inches total. I would worry about cavitation in the pump.

Personally, I try to run as large of tubing as possible all the time, and reduce it close to the end of I have to.

Dan

[xchrisjb]

Dan's right -- two 1" intakes won't be enough. Don't know what I was thinking when I typed that ...

You need at least 1.5" pipe on the inlet(s). Still I'd go for two intakes, each one being 1.5".

[BeanAnimal]

(2) 1" intakes will be enough if you are comfortable with the steps needed to balance the output. The restriction on the output side will help to balance the restriction on the input side. That may mean adding a ball valve before the OM to throttle the pump.

In other words... when you reduce the intake side of the pump, you need to reduce the output side to force the pump to operate at a lower flow. This will help to prevent cavitation.

You could get a dart to run on a 1" input if you were comfortable with the reduction in flow that would be required at the output side.

Remember output restriction is not hard on the pump, the pump just sees it as increased head.

Bean

[xchrisjb]

Bean --

Maybe you can help me out here. I recall reading here on RC that the "rule-of-thumb" for preventing cavitation in our pumps is that the size of the pump intake needs to be greater than or equal to the pump outlet (as seen on the pump itself, not necessarily the pump plumbing). Is this correct?

Based on that, I thought that with the 1.5" output on the pump, you'd need at least 1.5" of intake ... Yeah the pump sees the reduction down to 1" pipe on the return as an increase in head which results in a flow loss and a reduction in power consumption, but I'm not sure how that relates back to the operating pressure around the impeller. Isn't that what causes cavitation?

Now please don't think that I'm saying you're wrong. I'm not doing so at all. I'm looking for clarification of what I understood, which admittedly is based on a somewhat unreliable source (the internet). I think I need to go off and study up on cavitation.

Hope this isn't too much of a hijack, EnderG60!

[newnano]

i had a snapper on a closed loop and reduced the intake to 1.5 and the output was 1.5 for about 1.5-2ft then going to 1. worked well

[BeanAnimal]

Yes when you reduce the intake, you need to reduce the output. If you do not, the pump will clear the volute and try to draw a vacuum because it can not pull water in fast enough.

Cavitation is kinda complex and can be casued by several things. The most common problem we will find with pumps of our size is the simply inability to get water into the volute as fast as it is being pushed out. This does decrease the pressure around the impeller and vacuum pockets begin to form as the water is pulled apart as the impeller tries to draw it in faster and faster from the intake.

Choking the output down will reduce the overall flow of the pump. You can look at this as in increase in pressure, or a decrease in overall flow. In either case, the Bernoulli equations will show you the relationship.

By valving the output, you can dial the overall pump curve in to fit the input side without cavitation. You may not be pleased with the overall flow results...

Does that help?

[xchrisjb]

Thanks. I think it does help.

[EnderG60]

ok great, thats exactly what I needed to know. I will just go ahead and use 1.5" and 1" then and use a ball valve to balance the flow up to the OM.

now second part of the issue. We are going to get a super squirt OM but do we use the regular one with 1" piping or can we get away with using the compact SS that has the 3/4" threaded ends, and using 3/4" the rest of the way? This part im very unsure of. Id love to have the threaded SS but 3/4" sounds way to small for something pushing over 2000 gph.

[jessezm]

hmm... I would think it might depend on which version drum you have, given that some only give you one port open at a time, and others more. I think either way, though, I would be a bit uncomfortable with 3/4" returns... Only one way to really find out...