surge tank questions

jamielind · #1 12/23/2007, 09:21 PM

i was thinking about using 2 surge tanks for my next tank. one would use a 2500 gph feed pump the other 1000 gph pump. what size pvc pipe would i use for a siphon surge. i would guess to big it wont siphon and to small tank would overflow.

ls7corvete · #2 12/23/2007, 10:48 PM

Those are big pumps for a surge tank.... Maybe you should go with educators?

jamielind · #3 12/24/2007, 08:52 AM

it is for a very large tank. no one knows what size to use?

little_squid · #4 12/24/2007, 11:32 AM

imo it depends on the size of the surge tank

jamielind · #5 12/25/2007, 02:40 PM

i was thinking 2 - 200 gallon surge tanks

Siffy · #6 12/25/2007, 04:44 PM

How long do you want the surge to last? 15-30 seconds would be doable here. Or longer if you prefer.

200 gallon in 15 sec -> 48000gph

Plug that into the drain calculator on RC's homepage -> 9.05in diameter

200 gallon in 30 sec -> 24000gph -> 6.4" dia

But you'll get a little higher flow and thus shorter surge due to the head height inside the container. I'd go with a 4 or 6" pipe with a flapper design. That way you won't have to worry about starting a siphon or having as many air bubbles.

Siffy · #7 12/25/2007, 04:45 PM

Also, how large is the tank? Area-wise LxW? Also, you could go with an 8" pipe for a short very powerful surge, but remember the tank has to be able to handle it as well.

kgross · #8 12/25/2007, 06:20 PM

How high above the main tank are the surge tanks going to be mounted? If it is more than a few feet you should be ok with 2 inch pipe, if not, you are going to need 3 or 4 inch pipe to get a good quick dump.

Kim

jamielind · #9 12/25/2007, 08:50 PM

plan is the bottom of surge tank is 1' above water level of display. i want it to surge as hard as possible im just worried that if i use to big of pipe it will be to hard for the pumps to start a siphon. like if your toilet stays runing its not enough water to start a real flush. i want to stay away from the flapper design just because it seems to problem prone. thanks for the advice so far please keep it coming. also the tank will be able to stand as much as i put in it.

jamielind · #10 12/25/2007, 08:55 PM

the dimensions on the tank as of now are 12' long 4' wide and 5' deep. it is going to be poured concrete with a 10' X 4' viewing area. this might change as the foundation for the house is not going in till spring. just trying to figure things out a little before hand

JCTewks · #11 12/26/2007, 12:27 AM

I think you'd be better off using actuated valves on a surge system that size. They are pricey, but if you're doing a tank this size, what's another grand

Siffy · #12 12/26/2007, 12:35 AM

I haven't heard any problems like that with a flapper design. If it's built well, you shouldn't have any problems (and would actually have less noise and fewer bubbles in the tank), but it's your call. You could also go with an actuator driven ball valve controlled by a float switch in the surge tank.

I asked the tank size to do the math on the rise of water. A 200g surge into a 1800g tank will raise the water 6.68".
(200g * 231in^3/g) / (12ft * 12in/ft * 4ft * 12in/ft) = 6.684027778in

Imagine if both surge tanks started at the same time. Can the tank handle an almost 13 1/2" rise in water height in a manner of seconds?

I'd still go with 4 or 6" pipe. I don't believe a 2" surge pipe will be what you're seeking. You could try both, honestly. The cost of one or two sticks 2" or 3" pipe and a few fittings is insignificant considering the magnitude of this project. I would also recommend bending the pipe yourself or buying a couple long radius/sweep 90s per tank. Lowes/HD do carry them, for electrical conduit. Even though usually not recommended (even by myself), they will hold water but I suggest extra care when gluing. I would attempt bending the PVC with a heat gun first, and the cantex (electrical fittings) option as a backup. IThe U shaped 180 should help the siphon start, I believe.

Regardless, I expect video of it in action by this summer!

jamielind · #13 12/26/2007, 10:42 PM

where would i find a flapper for a 4 or 6 inch pipe?

kgross · #14 12/26/2007, 11:24 PM

I think you would have to make your own flapper for the large pipe.

Kim

strayvoltage · #15 12/26/2007, 11:32 PM

If you haven't already looked at the thread about the new tank set up at St. Judes, then you should have a look and read at least the part of it about the surge tanks and how they work. I think you will find it in the large reef section here on RC

strayvoltage · #16 12/26/2007, 11:34 PM

On that thread they also have a couple of videos of the surge in action.

strayvoltage · #17 12/26/2007, 11:41 PM

Here you go, I went and found it for you.
http://archive.reefcentral.com/forum...readid=1196137

H20ENG · #18 12/27/2007, 12:04 PM

I've built a few big surges. If you dont want slurping and bubbles, then you will have to go with actuated valves (pneumatic butterfly for 4" or larger- quick acting), or a pneumatic ram based plunger disc.

You want the valve or flap to close before sucking air, this way it stays quiet.

You will need to have a large overflow or lots of freeboard to contain the surge.

Let me know if I can help

ckoral · #19 12/27/2007, 04:51 PM

I was wondering where the best place to purchase pneumatic valves? Those are nice.

jamielind · #20 12/27/2007, 11:05 PM

well i think i will 4" pipe and either a flapper or valve. so next ? is is it possible 2 - 200 gallon surges thru 4" pipe 1 ran off a 1000 gph pump and one ran off a 2000 gph pump would be enough flow for that size tank. if not i was thinking id round the inside corners of the tank and get some prop type pumps to create a circular flow in the tank. thanks for all the great help so far.

jamielind · #21 12/27/2007, 11:07 PM

and yes the tank will be able to hold the 13" inches of water if both discharge at once. ill just have to remember to keep the lights a little higher

JCTewks · #22 12/28/2007, 02:07 AM

The tank won't have to actually hold 13" of extra water. Are you using a large wier type overflow? If so, You just need a couple of extra standpipes about 3" dia that are set just a tad higher than the main standpipes. Then, when the surge fires, the water level in the overflow box rises and is accommodated by the extra, higher, larger standpipes and goes back to the sump. Your sump will need to hold the extra 400 gal all at once though. Surges are great...but in that volume, they make an ATO tricky to setup. Just make sure you have a HUGE sump.

jamielind · #23 12/28/2007, 09:21 AM

i was planning on using 2 sumps one to hold equipment. and a lower one to hold the surges. the lower one i have its a 500 gallon fiberglass tank. the overflow will be like a gutter on a swimming pool it will have 4 - 4" pipes going to the sumps. i also have a 220 gallon tank to use as a refugium. the surges are going to come in at the bottom of the tank. im just wondering how much more flow ill need. noise is not a problem neither is humidity this will all be in a basement garage except for a viewing panel in my basement.

H20ENG · #24 12/28/2007, 11:47 AM

Ckoral,
I got my valves from my local PVC distributor.

I set up the 250G surge tanks to drain through 4" pneumatic valves (see my gallery for the system). There were 2 of them. Dont forget the overflow standpipe in the surge tanks!

I set one valve timer at 12 seconds, and the other at 10 seconds. This didnt quite drain the surge tanks, and they were about 6-8' above the exhibit. That is a lot of head. So either get the tanks up higher or leave the valves open longer to use all the water in the surge tank.

The cool thing was the surges were offset with the different valve timing, but over time they would catch up to each other and fire at the same time. LOTS of water all at once, so you need to account for BOTH firing at once in your drain calcs (unless you use an interlock between the timers).

Your setup sounds good so far. Topoff is not really an issue, you just have to set it up so it adds topoff water when both tanks are full. This will be the lowest level in the sump. Your sump needs to be large enough that it can take all the surge water, but still not run dry when both surge tanks are full.

I had the tanks on a constant fill and turned the valve timers off at night. The water simply overflowed the standpipes until morning when the timer turned back on. The first surge of the day was the most spectacular since both tanks were brimmed and both fired at once.

During the day, a float switch triggered the valve timer, which trips a solenoid valve, sending air to the valve actuator. You could also set it up using 2 floats instead of a timer, as long as they are on an adjustable rod.

With bigger valves, you need air driven actuators. The electric ones for that size valve are waaay too slow.

HTH,
Chris