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No. 56000 Bubble-Tight <500 ppm Pressure Relief Vents

Series No. 56000, Bubble-Tight

Series No. 56000, Bubble-Tight <500 ppm Pressure Relief Vents are designed and tested to address concerns about the leakage of fugitive emissions prior to set point, and parts per million (ppm) emission rates.

Protectoseal’s PIN-TECH vents are mounted to the vapor space flange connection of a storage tank or vessel. The vents utilize a unique technology that employs a buckling pin to hold the vent piston closed (Fig. 1) with zero leakage up to the relief set point. The pin is an accurately machined, straight metal rod. It is configured to precisely sense transmitted axial forces that are generated as a result of tank pressure. The force required to buckle the pin is governed by Euler’s Law and is a function of the pin’s metallurgy, length, and diameter. An exact buckling force can be determined for any specific pin configuration. When the pressure in the tank reaches the vent set point, the axial force is sufficient to buckle the pin and the vent sealing piston is allowed to move to its fully open, relieving position (Fig. 2). The pin buckles completely and instantaneously.

Environmental Regulations: Protectoseal’s PIN-TECH vents provide a means of complying with the stringent VOC emission requirements mandated by the United States Environmental Protection Agency (EPA) outlined in the Code of Federal Regulations (40 CFR).

  • Sizes Available: 2″ (DN 50) thru 24″ (DN 600)
  • Set Point Range: Pressure settings from 1 oz/in² to 15 PSIG.
  • Sealing capabilities to less than 500 ppm
  • End-of-line pressure, end-of-line vacuum, and in-line (pipe-away) configurations
  • Relief settings from 1 oz./in.2 15 PSIG
  • Full open at the set point
  • Accurate/repeatable set points
  • Reduced maintenance costs
  • Factory tested for leakage and correct settings
  • Optional testing and certification for less than 500 ppm


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