LPG Tank Fill Time

5000 liters ÷ 30 minutes ≈ 167 l/m (~40 gpm) pump rate at 50 m (~160 ft) head. As a rough guess, this would call for about a 40 mm (1.5 inch) hose or pipe. What can your bulk LPG supplier provide that would be roughly proportionate to this? That's just a quick take.

We are trying to get the supplier's data on what can they only produce. A just one question, are we considering the static head (50m) for the head? If the operating pressure of the Bulk tank is 70 psi, should we add this to the head?

Yes, and then subtract the pressure in the delivery tank. Better yet, consider Tcmtech's approach.

Don't the building codes gods have something to say about putting that big of tank up there?

And why do it in the first place?

What ever you have up there wont use as much fuel at at time as what the required filling lines would need to carry when factoring in any reasonable filling times.

So why have it up there when it can be on the ground and push its own vapor up to that level with a much smaller less costly lines and far less pressures as well.

A 20 PSI feed off of a pre regulator mounted on the tank will push propane vapor far higher than any building stands!

We did have that conversation with the client berfore. I believe NFPA recommends the tanks to have a certain distance away from the building wall which the client doesn't want to reduced the saleable areas. So the direction is to place it on the roof deck.

Please correct me if I'm wrong, isn't LPG vapor heavier than air? so it do gain pressure going down?

I do believe the local authority approved the scheme.

Pardon me, but this plan sounds a little whacky to me. The propane truck uses a positive displacement pump to deliver the fuel. It expects to pump into a tank, against a cushioning pressure, up to a certain pressure limit. I imagine the roof tank head will exceed that pressure, that's why they balked.

If you try to pump a positive displacement pump into another positive displacement pump, even if they were identical, I think you will experience problems. At one moment the driving pump may be over-pressured, and a relief valve will return the fuel to it's tank. At the next moment the booster pump will be starved and may break it's vanes trying to pull a vacuum. Water hammer may enter the situation and threaten to burst pipes.

At the very least you will need a tank between the pumps to smooth out the pressure.

thanks Mike, that why it's confuses me in the first place when the supplier told our engineers on site that they can't supply the tank on the roof when they supposed to have fill pump on their tankers.

thanks to you guys for your inputs..

Can you not have underground tank?

Propane vapor is about 1.5 times heavier than air. A Coulomb of air that represents our atmosphere weights around 14.8 pounds at sea level an average. A Coulomb of propane vapor of equal hight would be around 22.2 pounds. So if you where using a tank regulator set only to 20 PSI over the ambient air pressure you could still run a heater on the space shuttle if you needed too!

Over all this just sounds like moronic businessmen trying to be engineers in an area that they have absolutly no clue about what they are doing.

Leave the tank on the ground, your financially much further ahead.

I still don't get how they require the tanks to be a specific distance away from the building yet being on top of it would be seen as okay?

Plus a 5000 L tank would be equivalent to being between the 1250 and 1500 gallon American tank sizes. Which would make it weigh around some 6000+ pounds when full.

Some of this is just not adding up for some reason.

due to the limited space the client want to maximize the area. that is the restriction for us not to locate the and above-ground tank on ground floor level.

NFPA 58 thus allow tanks on the roof not exceeding 4000 gal capacity and as long as the Containers are located in areas where there is free air circulation, at least 10 ft (3.0 m) from building openings (such as windows and doors), and at least 20 ft (6.1 m) from air intakes of air-conditioning and ventilating systems.

The tanker has a pump. Disconnect it make direct pumping to the roof tank with your own new pump. I pressume that the tanker pump has a suction valve.

Easy--they have, or can get cheap, a big tank; and it needs some way to be used; and there are no shortage of rrr-rational justifications. Or they want to go into ceramics, tile, or bricks on a big scale.

What we do here is to bury the tank underground......solves most problems, but the tank needs to be (Fiberglass resin?) lagged to stop rusting etc...