The delivery procedure
Standard residential delivery follows a five-step sequence:
- Driver inspects the tank, regulator and fittings for any visible issues
- Truck hose connects to the fill valve (standard ACME thread)
- Liquid level valve opens — vapor escapes from this tube while the tank fills with liquid below it
- Pumping continues until liquid (not vapor) sprays from the level tube — that's the 80% fill signal
- Driver records gallons from the truck meter, completes paperwork, leaves the receipt
Why 80% and not 100%
Liquid propane expands and contracts significantly with temperature — about 0.1% per °F. Filling to 100% on a cold morning could result in liquid pressure pushing through the relief valve as the day warms. The 80% rule leaves 20% headroom for thermal expansion and is required by NFPA 58.
What you pay for
Your invoice shows: gallons delivered (the 80% volume), per-gallon rate (from your contract), and any per-delivery surcharges (hazmat, fuel, after-hours). Tank rent is billed separately, usually annually. See what dealers charge for the full fee structure.
FAQ
Can the driver fill above 80%?
No. NFPA 58 sets 80% as the absolute maximum, and CETP-certified drivers are trained to stop at the liquid level signal. Any reputable dealer enforces this strictly — overfilling creates serious safety risk.
How long does a delivery take?
Typically 10–20 minutes for a residential 500-gallon fill. Longer for very large tanks or for tanks that have run completely empty (post-runout leak test required by NFPA 58).