What the markings on your LPG cylinder mean
The markings on a Pakistani LPG cylinder record its manufacture date, manufacturer, next test date, company, serial number, batch number, tare weight and water capacity. The next-test date is the one commonly mistaken for an expiry date. It tells you when the cylinder is next due for pressure testing.
Every cylinder carries its own record, stamped into the collar or the shoulder ring. Once you know what each field is, you can check a cylinder in about ten seconds at handover.
Where are the markings?
On most Pakistani cylinders they are embossed into the protective collar around the valve, or into a plate welded to the shoulder. They are stamped rather than printed, so they survive handling and repainting.
What does each field mean?
| Field | What it tells you |
|---|---|
| Manufacture date | When the cylinder was built |
| Manufacturer name | Who built it |
| Next test date | When it must next be pressure-tested |
| Company name | Whose cylinder it is |
| Serial number | The individual cylinder's identity |
| Batch number | Which production run it came from |
| Tare weight | The empty weight, in kilograms |
| Water capacity | The internal volume, in litres |
Which marking is the tare weight, and why does it matter?
The tare weight is the weight of the cylinder empty. It is the single most useful number on the cylinder, because gross weight minus tare weight is the gas you actually received.
If a cylinder is stamped 15.5 kg tare and weighs 27.3 kg full, you received 11.8 kg of gas. That arithmetic is how you check you were not short-filled.
Is the next-test date an expiry date?
No. It is the date by which the cylinder must be pressure-tested again before refilling. A cylinder that passes is stamped with a new date and returns to service.
This is the field the viral expiry messages misread. Pakistani cylinders do not carry an expiry date at all.
What if the markings are unreadable?
Refuse the cylinder. A cylinder whose stamps cannot be read cannot be verified, cannot be weight-checked against its tare, and should not be filled.
Common questions
Where is the tare weight written on a gas cylinder?
It is embossed into the protective collar around the valve, or into a plate on the shoulder, usually shown in kilograms. Subtracting it from the full cylinder weight tells you exactly how much gas you received.
What is water capacity on a cylinder?
The internal volume of the cylinder in litres. It is a construction specification used in filling and testing, and it is not the same as the weight of gas the cylinder holds.
What should I do if the markings are worn off?
Refuse the cylinder. Without legible stamps you cannot confirm the next-test date or check the fill weight against the tare, and the cylinder cannot be properly verified before filling.
References
Sargodha Gas has supplied LPG cylinders in Sargodha since 2005. Contact us