Tech Talk - Small LP tanks fire pit operation and concerns - Gas Fire Pit and Fireplace Blog

Hearth Products Controls Co.

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Tech Talk - Small LP tanks fire pit operation and concerns

HPC Fire Inspired™ Tech Talk this week is going to talk about 20lb LP tank facts and how they relate to your fire feature, and how to better understand the operation of your fire feature.

Let's start with some facts to help understand LP delivery from a 20lb tank:

  • Small tanks weigh 20lbs when empty, and will be filled with approx. 4.1-4.5 gallons of LP
  • Small tanks can only be filled to 80% capacity to avoid over venting large amounts of LP, when the ambient temperature rises
  • One gallon of LP will contain 91,502btu's per hour, at best a full tank will provide 375,158btu's and are limited to smaller appliances
  • Each tank will have a OPD valve (overfill protection device) to prevent over-filling of the tank
  • The low pressure regulator should include a surge protection device to eliminate too much gas from escaping the tank at once

Keeping in mind the above facts, let's see how they pertain to HPC Fire Inspired™ features:

  • With the limited capacity of the small tanks, fire feature sizing becomes critical, as the tank cannot supply the proper gas supply to larger units
    • HPC Fire Inspired™ recommends no appliance higher than 90,000btu be connected to a small tank
      • HPC Fire Inspired™ small tank certification is limited to 90K and below
  • Burn time will be limited and can be calculated. For example, let's take a 65K fire pit burner:
    • Maximum fill of 20lb tank = 4.1 gal
    • 4.1 gal X 91,502 = 375,158btu
    • 375,158btu/65,000btu = 5.77 hrs. of burn time per 20lb. tank
  • Proper ignition and operating instructions must be followed to prevent excessive gas from leaving the tank too quickly and limiting gas flow through the regulator
    • This will cause small flames and erratic flame pattern
      • Unit will have to be shut off, and time given to allow the tank/regulator to reset
So with the information above, below are some things to keep in mind when using a small tank on your next fire feature project:
  • Sizing of the fire feature must be kept to 90,000btu units and below
  • Electronic ignition units cannot be operated on a small 20lb LP tank
  • If extended burn times are critical than other means of gas supply must be considered
  • Always follow ignition start-up and shut down sequence to prevent limited flow of gas through piping system
  • Always ensure proper ventilation as described by the manufacturer is in place before operating unit
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