Refilling 3.9 kg Calor botas.

[Graham_Wright]

I have successfully refilled several but the last is within 7.5 kg instead of ~ 9.5.
The refill cylinder is about half full and has filled others since this failure.
Any suggestion why please?
I assume it is impossible to overfill them as when it's full it's full.

 

[vyv_cox]

Bottles should only be filled to about 80% to avoid allowing liquid fuel to the appliance. The net weight is usually marked on the bottle but a useful tip is to float the bottle in water. When it sinks it is just right. Works for Calor 3.9 and for Camping Gaz 907.

 

[neil_s]

I believe it's also very unsafe to fill them completely - you must leave some expansion space for the liquid. The gross and tare weights are marked on the bottles.

 

[andsarkit]

The process is very temperature dependant and the donor should be warmer than the receiving bottle. I had a very slow filling that almost stopped. When I warmed the donor with a kettle of water it speeded up and I was not watching it closely enough and it overfilled. Venting off the excess was easy enough to bring it down to 80%. In this cold weather the bottles might take a long time to warm up sufficiently. I assume it is propane as butane has very little pressure when cold.

 

[superheat6k]

Moving liquid LPG is the same process as used for charging refrigerant into a system. As advised do not wedge them full with liquid - the cylinder could explode due to liquid expansion - liquid expansion due to temperature changes is an immense force - no gas space = no room for expansion.

The issue is likely a cold donor - as the liquified gas leaves the donor some will flash off making the donor colder than the receiver, and hence the pressure within lower. Leave in the warm for a few hours, with the receiver outside in the cold, this should promote good flow.

 

[MontyMariner]

Any suggestion why please?

It's been bloody cold, that could be a reason.

 

[VicS]

It's been bloody cold, that could be a reason.

It has not been cold enough to make filling a propane cylinder difficult..
.

 

[Graham_Wright]

But! I said that I had filled others successfully subsequently. I fill so that the tare weight plus 3.9 is the target ~ 9.5kg.

 

[Metalicmike]

Are you pumping the liquid gas into the bottle or relying on differential pressure and gravity. If you are not pumping then as the supply vessel reduces in volume it will loose temperature and pressure quicker and your fill rate will drastically reduce.

 

[neil_s]

But! I said that I had filled others successfully subsequently. I fill so that the tare weight plus 3.9 is the target ~ 9.5kg.

Sorry! I'm a Campingaz bottle user so not aware of the Calor weights.

 

[Boathook]

I use calor 4.5Kg butane bottles and weigh them when empty. I have found that the weight of an empty bottle does vary by nearly 1Kg.

 

[DownWest]

Think I told this story before... (age etc..)
But when we were top dressing forestry off a hill strip strip near Lockabie, sometimes the weather(and vis) clamped down, so we sat it out in a caravan and played cards.
Winter, so bloody cold, but there was a gas heater running of a bottle outside. Natch, the cold reduced the flow to zero, so no heat.
The Finnish pilots just went out, drained a bit of Avgas from one of the planes, chucked it on the ground and set light.. Put the bottle on and the flow cheered up no end. The first time, I asked one if it wasn't a bit dangerous?? He, ' Not if there isn't a leak in the connections'. Back to playing cards...

 

[Graham_Wright]

But

Are you pumping the liquid gas into the bottle or relying on differential pressure and gravity. If you are not pumping then as the supply vessel reduces in volume it will loose temperature and pressure quicker and your fill rate will drastically reduce.

!
I say again, I subsequently filled the bottles!

 

[MontyMariner]

I say again, I subsequently filled the bottles!

So think back and list what changed between when they didn't fill to when they did. . .
Has the one that half filled now filled?

 

[Graham_Wright]

So think back and list what changed between when they didn't fill to when they did. . .
Has the one that half filled now filled?

Nothing and I'fe been round the loop a couple of times. I think I'll empty it and start afresh.

 

[BobnLesley]

We got quite adept at decanting gas while we were sailing about and used a cheap spring balance to avoid overfilling: Weigh the empty receiving bottle, leave it hanging on the spring balance while you're decanting and stop filling when it's got 3.9kg heavier. The transfer will get slower with each decant and you won't ever get the final kilo or two of gas to transfer. Besides hanging the donor bottle upside down and at least a metre (preferably two or three) higher than the recipient bottle, also try to have the donor bottle significantly warmer than the recipient bottle when you transfer.

 

[BobnLesley]

But! I said that I had filled others successfully subsequently. I fill so that the tare weight plus 3.9 is the target ~ 9.5kg.

Is it exactly the same bottle? Some bottles (the US ones spring to mind) had a pressure release screw in the side of the valve, which you had to screw out a bit to get the gas to go in.