Propane Tanks

Propane tanks come in a variety of sizes. The choice of size depends on the type and number of appliances to be supplied.

Below is a full list of tank sizes as supplied by Lamprey Energy.

57 Gallon

  • Capacity: 45.6 gallons
  • Supplied for:
    • dryer
    • gas grill
    • stove
  • Placement: above ground
  • Concrete pad requirement: round, 2"-thick, 24"-diameter

120 Gallon

  • Capacity: 96 gallons
  • Supplied for:
    • cast-iron heating stove
    • central heat (boiler or furnace)
    • construction heater (temporary)
    • fireplace
    • garage heater (Modine or Hot Dawg style)
    • gas log
    • generator
    • instant/tankless hot water heater
    • outdoor firepit
    • outdoor lighting
    • patio heater
    • pool/spa
    • zone heater
  • Placement: above/underground
  • Concrete pad requirement: round, 2"-thick, 30"-diameter

325 Gallon

  • Capacity: 260 gallons
  • Supplied for:
    • central heat (boiler or furnace)
    • construction heater (large)
    • generator (large)
    • pool heater
  • Placement: above/underground
  • Concrete pad requirement: two rectangular blocks, 4" x 8" x 30"

500 Gallon

  • Capacity: 400 gallons
  • Supplied for:
    • central heat (boiler or furnace)
    • construction heater (large)
    • generator (large)
    • pool heater
  • Placement: above/underground
  • Concrete pad requirement: two rectangular blocks, 4" x 8" x 30"

1000 Gallon

  • Capacity: 800 gallons
  • Supplied for:
    • central heat (boiler or furnace) for commercial application
    • central heat (boiler or furnace) for large home
    • construction heater (large)
    • generator (large)
  • Placement: above/underground
  • Concrete pad requirement: two rectangular blocks, 4" x 8" x 30"
Reading Your Propane Tank Gauge
Number of Gallons Remaining
Gauge Reads 57 gal tank 120 gal tank 320 gal tank 500 gal tank 1000 gal tank
80% 46 96 256 400 800
70% 40 84 224 350 700
60% 34 72 192 300 600
50% 29 60 160 250 500
40% 23 48 128 200 400
30% 17 36 96 150 300
If your gauge reads 30% or less call 603.964.6703 to request a delivery!
20% 11 24 64 100 200
10% 6 12 32 50 100

The Regulator

Every propane system must have a regulator. The regulator is needed to adjust the pressure from high (inside the tank) to low (required by the propane-burning appliance).

The regulator is made up of two main components:

  • The Vent
    • The vent allows the regulator to ‘breathe,’ allowing air to move into and out of the system during normal operations.
    • It also acts as a pressure release, preventing too much pressue buildup within the system. It is important that the vent is kept clean and clear from any obstruction that might restrict air flow.
    • It must also be protected from insects, water, snow, and ice and must therefore always be installed pointing down.
  • The Diaphragm
    • The diaphragm is a flexible rubber disc located inside the regulator. It senses pressure changes and moves freely up and down to adjust the gas flow to the correct rate.
    • Along with other internal components the diaphragm operates in conjunction with the vent to maintain safe flow rates and pressure. Appliances require a specific flow rate and pressure; the regulator will be adjusted to ensure the correct gas pressure at all times.

Anodes for underground tanks

Corrosion is a real threat to an underground propane tank but there are ways to significantly slow the process—almost to the point of eliminating it entirely. Corrosion is the gradual destruction of a material by chemical reaction with its environment. Most commonly, corrosion in a metal refers to oxidizing or rusting.

For underground propane tanks, which exist in a moist unseen environment, protection against corrosion is vitally important. Thus, underground propane tanks have a protective tank coating and are further protected by one or more sacrificial anodes.

How do anodes work?

When two metals are brought into contact with one another (either directly or indirectly) the metal that normally corrodes at a slower rate will corrode at an even slower rate, while the faster-corroding metal will corrode at a faster rate. This is called a cathodic reaction. The slow-corroding metal is a cathode, the fast-corroding metal is an anode. In the case of an underground propane tank, the tank is the cathode. In order to reduce or even eliminate the tank’s corrosion it is fitted with one or more anodes of either zinc or magnesium.

As the cathodic reaction occurs, the tank’s corrosion is slowed. As the chemical reaction occurs an electric current is created, charging the tank, the anodes, and the surrounding environment. This current offers further protection to the tank and it can be measured by a voltmeter. As the anode corrodes the current will decrease. Eventually the anode will be corroded away and the cathodic protection will be lost. The electric current will cease to exist. By regularly measuring the electric current around the tank we can tell if and when a new anode is needed.

Underground tanks below 1000-gallon capacity require one anode.
Underground tanks of 1000-gallon or greater capacity require two or more anodes.

Finally, it is important that the tank is isolated from the piping—without electrical isolation the anode will be called upon to protect the piping as well as the tank and the chemical reaction will be exaggerated. If the piping can not be isolated additional anodes may be required.

What’s Inside the Dome

Under the cap of a vertical propane tank, clockwise from far left: Fill (yellow), regulator (red) connected to the valve with shut-off (Grey), emergency vent (green), Gauge (bronze)

How to Read the Gauge

Propane is delivered and stored in pressurized tanks as a liquid. However, propane boils in temperatures down to -44°F, so inside the tank the propane liquid is boiling and turning to vapor (or gas). When the vapor reaches 100% humidity it turns back into liquid and the cycle is repeated.

Propane gas has a greater volume than propane liquid and so requires more space to contain it. Because of this a propane tank is never filled to 100%—there must always be space into which the liquid propane can evaporate, creating a pocket of gas at the top of the tank. It is this pocket of gas that is drawn off to fuel an appliance, not the propane liquid.

As the gas is drawn off, the pressure within the tank is reduced and so the liquid within the tank boils faster and more vapor/gas is produced. This process is constantly repeated as the gas is used up.

The tank gauge shows what percentage of the tank’s capacity is full.

The table below shows how many gallons tanks of varying sizes hold at varying percentages of capacity (remember it will never read 100% – full will be 80%).

Under the cap of a horizontal underground propane tank, clockwise from top left: Relief valve (black), liquid withdrawal valve (yellow, top), gauge (between the two yellow vents), fill pipe (large yellow), shut-off valve (silver at right), regulator (red) connected to shut-off.

Reading Your Propane Tank Gauge
Number of Gallons Remaining
Gauge Reads 57 gal tank 120 gal tank 320 gal tank 500 gal tank 1000 gal tank
80% 46 96 256 400 800
70% 40 84 224 350 700
60% 34 72 192 300 600
50% 29 60 160 250 500
40% 23 48 128 200 400
30% 17 36 96 150 300
If your gauge reads 30% or less call 603.964.6703 to request a delivery!
20% 11 24 64 100 200
10% 6 12 32 50 100
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