Can anyone give me a brief idea of how to blow liquid tanks off?
I’ve done plenty with powder tanks and I can imagine a liquid tanks a bit like a 1 pot belly tank without pad air. Is this the case?
Also when I’ve topped powder in the dark with a looking glass on the discharge pipe I’ve noticed spark like static. How do you blow flammable off or is it just gravity fed?
When I saw the title I thought you were complaining about being the victim of a dodgy Chicken Bhuna 
(Sorry mate never done tanker work)
Just wait til Dipper Dave sees the title! 
This thread was made for Dave! Please make it sticky so we don’t lose it haha
NickW88:
This thread was made for Dave! Please make it sticky so we don’t lose it haha
Stop making it worse!
jef:
Can anyone give me a brief idea of how to blow liquid tanks off?I’ve done plenty with powder tanks and I can imagine a liquid tanks a bit like a 1 pot belly tank without pad air. Is this the case?
Also when I’ve topped powder in the dark with a looking glass on the discharge pipe I’ve noticed spark like static. How do you blow flammable off or is it just gravity fed?
Liquids are straightforward, you pressurise the tank and then let 'er rip.
You are quite right that you don’t blow off flammables - these are only pumped (and in certain high-risk contexts, like forecourt petrol deliveries, the infrastructure is designed so that pumping is also eliminated).
You don’t use air to blow off liquids LOL, they all unload using a hydro pack pumping system. If you don’t have a hydropack you can’t possibly unload.
See the hydraulic lines running down the side of the trailer ? They connect to a hydraulic pump on the tractor chassis. If the trailer does not have a system like this, and there is no liquid pump visible on the trailer, either at the rear or if a belly tank, underneath the belly then the customer you are delivering to should use a system of their own to pump the load off. As very rarely do customers (with the exception of fuel deliveries) use gravity.
Rjan:
jef:
Can anyone give me a brief idea of how to blow liquid tanks off?I’ve done plenty with powder tanks and I can imagine a liquid tanks a bit like a 1 pot belly tank without pad air. Is this the case?
Also when I’ve topped powder in the dark with a looking glass on the discharge pipe I’ve noticed spark like static. How do you blow flammable off or is it just gravity fed?
Liquids are straightforward, you pressurise the tank and then let 'er rip.
You are quite right that you don’t blow off flammables - these are only pumped (and in certain high-risk contexts, like forecourt petrol deliveries, the infrastructure is designed so that pumping is also eliminated).
You should NEVER pressurise a liquid tanker, it could result in disaster.
Having worked for a company that delivers both liquid and powder for the last 10 years, I hope this has helped you 
DON’T forget to vent the tank before you start to unload !!! It will implode.
Pat, you do and I have pressurised a liquid tanker with an air compressor, build up to 2 bar and open the valve, it empties 35000 litres in about 30 mins, hope this also helps (hazardous) by the way.
Sapper
Pat Hasler:
Rjan:
jef:
Can anyone give me a brief idea of how to blow liquid tanks off?I’ve done plenty with powder tanks and I can imagine a liquid tanks a bit like a 1 pot belly tank without pad air. Is this the case?
Also when I’ve topped powder in the dark with a looking glass on the discharge pipe I’ve noticed spark like static. How do you blow flammable off or is it just gravity fed?
Liquids are straightforward, you pressurise the tank and then let 'er rip.
You are quite right that you don’t blow off flammables - these are only pumped (and in certain high-risk contexts, like forecourt petrol deliveries, the infrastructure is designed so that pumping is also eliminated).
You should NEVER pressurise a liquid tanker, it could result in disaster.
Tipped lots of bulk vinegar using air pressure, never had any disaster’s
It is perfectly acceptable to pressure discharge certain liquids Pat. Could you imagine pumping off Oleum or Nitric acid and having to get rid of a minimum of two pipe fulls of product?
As has been said though blowing off flammable a is frowned upon although I have done it in the past using the customers air and also late on a Friday night using my own compressor after convincing the stores guy that Methanol was only flammable when exposed to daylight and so was fine for me to blow it in the dark!
Sorry Pat, I think you’re getting confused. Hydrapak can power pumps or compressors. Some of the tanks we use have both. There is a lever to select hydraulic power to the pump or the compressor, and the compressor definitely pressurises the tank, 2 bar in our case for bitumen, if there isn’t a ground based customer pump. HFO/MFO/ Gas oil is usually wazzed in with the pump.
Most liquid I’ve delivered has usually been blown in, some even with a bit of pumping beforehand. 
Bitumen: Attach your pipe to the open flange, and blow in your hot liquid.
ive got to say if you havent been trained then you shouldn’t be doing it in any way shape or form, with a powder tank the product is carried along with the air from compressor,withit liquid it is pushed by putting pressure into the tank,by pumping either with your own pump or the customers pump,you must vent the tank to stop it imploding,or by gravity again you must vent the tank.
if you are blowing the product,you connect to discharge point,open valves and let product flop into piework,why? because if there is a leak it will be a small drip ,you then shut down ,fix connection and start again,should the tank be under pressure at that point it would be a squirt and not a drip which is more dangerous
there is exceptions to this method such as when carrying products at elevated temperatures, they are carried at temperature and would go sticky/off if allowed to flop into pipe and sit while you built up the pressure therefore making them impossible to flow the pressure is built up before the valves are open as in bitumen
i hope this helps but refer to line one for the real advice
the maoster:
It is perfectly acceptable to pressure discharge certain liquids Pat. Could you imagine pumping off Oleum or Nitric acid …
That’s just saved me from some typing.
the maoster:
… after convincing the stores guy that Methanol was only flammable when exposed to daylight and so was fine for me to blow it in the dark!
You’d never have got that one past me, but you’d score 10/10 for invention. 
the maoster:
As has been said though blowing off flammable a is frowned upon although I have done it in the past using the customers air and also late on a Friday night using my own compressor after convincing the stores guy that Methanol was only flammable when exposed to daylight and so was fine for me to blow it in the dark!
There are various risks with pressurising and blowing off flammables, including that you have to deal with an increased volume of vapour and be aware of vapour leaks. Of course, some liquids that are treated as flammables, like diesel, do not have this problem.
There’s also the issue of depressurising the tank in various kinds of emergency.
Hi jef, This is me carrying out a pump discharge on a fuel tanker. Very simple to operate you simply connect to customers tank, connect the jumper hose, that’s the short hose going over the hose rack. Switch on P T O on unit open foot valves and outlet lever and let it go slowly at first to make sure there are no leaks, you just change the jumper hose after each compartment empties.You have a lever that has forward stop and reverse on it, You only reverse the pump to pump fuel back into your compartments. (Not used a lot)
Pat Hasler:
You don’t use air to blow off liquids LOL, they all unload using a hydro pack pumping system. If you don’t have a hydropack you can’t possibly unload.
0See the hydraulic lines running down the side of the trailer ? They connect to a hydraulic pump on the tractor chassis. If the trailer does not have a system like this, and there is no liquid pump visible on the trailer, either at the rear or if a belly tank, underneath the belly then the customer you are delivering to should use a system of their own to pump the load off. As very rarely do customers (with the exception of fuel deliveries) use gravity.
The norm on UK general tanker work is a hydraulic pump at the back, mainly used for loading and air blowing the load off
Pat Hasler:
DON’T forget to vent the tank before you start to unload !!! It will implode.
Not if you use air pressure to discharge…
(Ten years on milk tankers)
