Is there a plumber in the house?

[Dust Buster]

I'm trying to connect two WMI tanks together to extend my range. I want to be able to raise the smaller tank on the right to fill both tanks. I could crack open the non-vented cap in the larger tank to accomplish this (vs pushing against the airlock).

Two_tanks_design.PNG

I was thinking of using a 3/8” flexible, fuel hose to connect the two tanks, although I have plenty of available 1/8” fuel tubing. By placing the hose from the smaller tank into the “water” in the larger tank, I was hoping the pump would create a partial vacuum and pull the “water” from the smaller tank. The tops of the two tanks are at the same level, as depicted.

If needed, I could purchase another vented cap for the larger tank or possibly better, install a second tube connected the top of the two tanks.
I've been trying to read about header systems and feed and expansion system designs, but haven't found anything to verify this design. Will this work as hoped?

[Bill Chase]

just use a lift pump or have the smaller tank gravity feed into the larger with a check valve that prevents backflow.

[Nut124]

As drawn, it would appear that the upper tank will not start to drain into the lower tank as the upper tank level is always lower than the high spot of the connecting hose.

You would need to lift the upper tank so all of it is above the lower tank and vent the high spot air spaces in each tank together.

[Dust Buster]

just use a lift pump or have the smaller tank gravity feed into the larger with a check valve that prevents backflow.

I was hoping to stay passive, but could look at a check valve if it flowed into the smaller tank.

[Dust Buster]

As drawn, it would appear that the upper tank will not start to drain into the lower tank as the upper tank level is always lower than the high spot of the connecting hose.

You would need to lift the upper tank so all of it is above the lower tank and vent the high spot air spaces in each tank together.

Perhaps I didn't draw it correctly. The tops of both tanks are at the same level. However, the larger tank's lowest portion is lower than the smaller tank's.

As I would fill both tanks from the smaller tank by lifting it first, this should prime the connecting hose with “water”. My hope is that it would then act like a siphon.

Both tanks are at maximum height, but the tops are level with each other.

My, admittedly, poor understanding of the use of expansion tanks in a multi-level system is that the expansion tank maintains pressure in the closed system. That is, none of the designs that I saw vented the expansion tank. However, I could be wrong. I just want the siphon to work and am willing to vent between tanks or just add a vented cap to the larger tank. In that way, both ways would be pressure equalised to atmosphere.

[chimpvalet]

This layout could be made to work, as anyone familiar with use of a water level will acknowledge. DB is correct in that the lower tank will replenish via siphon as the pump draws fluid however a better design would eliminate the siphon, instead using low side fittings on both tanks for liquid and re-purposing a shortened original pipe at the top of the bottom tank as breather equaliser. Liquid will then easily maintain parity between the tanks. I'd advise use of the 3/8 line for fluid and 1/8 for the breather will suffice.

Cheers

[lefty o]

since you say they are both at the same height etc, i would just skip the whole siphon deal. if you have a siphon, you can lose the siphon for any number of odd reasons. instead, i would use vented caps on both tanks, and take the output from the bottom of both tanks into a y or a t at the bottom to feed the pump. both tanks will always be at the same level, and the pump fed by gravity or suction, no siphon. while a siphon could certainly work, it introduces too many variables.

[gunt]

vent both tanks you loose the benefit of the second , so thats a no , look at all the jap cars , they all vent off the rad cap , but aside from that

you need take a feed from the bottom of the vent tank to fill the first at all times so fill to a low point , then from the top of the first at the highest point and place it just under the vent point in the second [ can you not reweld the cap point on the vent one to its top ] but still so it would be under liquid as it makes a one way valve

[emsvitil]

Just T the output of the tanks together.

[Dust Buster]

This layout could be made to work, as anyone familiar with use of a water level will acknowledge. DB is correct in that the lower tank will replenish via siphon as the pump draws fluid however a better design would eliminate the siphon, instead using low side fittings on both tanks for liquid and re-purposing a shortened original pipe at the top of the bottom tank as breather equaliser. Liquid will then easily maintain parity between the tanks. I'd advise use of the 3/8 line for fluid and 1/8 for the breather will suffice.

Cheers

Water level - Yes, I should have drawn the two “water” levels at the same height.

I thought about connecting the lower ends, but wouldn't the higher bottom in the smaller tank empty first allowing air to enter the line?

3/8 for fluid and 1/8 for breather – thanks

[Dust Buster]

since you say they are both at the same height etc, i would just skip the whole siphon deal. if you have a siphon, you can lose the siphon for any number of odd reasons. instead, i would use vented caps on both tanks, and take the output from the bottom of both tanks into a y or a t at the bottom to feed the pump. both tanks will always be at the same level, and the pump fed by gravity or suction, no siphon. while a siphon could certainly work, it introduces too many variables.

The Snow pump is more of a pusher, than a puller. It is supposed to be level or below the input from the tank.

If I lower the smaller tank so that both tank bottoms are at the same level, will I still be able to fill the larger tank by raising the smaller tank when filling? I would think both tanks would need vented caps then.

[Dust Buster]

vent both tanks you loose the benefit of the second , so thats a no , look at all the jap cars , they all vent off the rad cap,

Actually, my radiator doesn't have a cap at all. The vented cap is on the expansion tank, where I add coolant.

but aside from that you need take a feed from the bottom of the vent tank to fill the first at all times so fill to a low point,

Understood

then from the top of the first at the highest point and place it just under the vent point in the second [ can you not reweld the cap point on the vent one to its top ] but still so it would be under liquid as it makes a one way valve

I'm now lost. Which is the first and second tank? I assume the first tank is the smaller tank. Yes, I can connect the tops of both tanks together. Both tanks are plastic and meths doesn't affect the plastic fittings that I will be using.

[Dust Buster]

Just T the output of the tanks together.

Can do

[Dust Buster]

What about using Engine vacuum to fill the tanks??

I made this device for a different purpose and it works great.

Interesting

In my forced induction engine, I assume that only the PVC line is in vacuum.

I'd be concerned with collapsing the non-ventilated plastic tank with a strong “suction”. The removal of fluid by the pump will create a mild vacuum by drawing slowly through the 1/8” tube.

[Dust Buster]

I think this is the current consensus.

Two_tanks_design_2.PNG