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Thief Hatch (Spring loaded)

  • Thief Hatch (Spring loaded)
  • Thief Hatch (Spring loaded)

Model No: 230

ERGIL Storagetech™’s Model 230 Thief Hatch offers protection against pressure and vacuum.

Within the cover are a static pressure seal, and a spring-loaded vacuum pallet and diaphragm assembly. The pressure and vacuum settings can be selected from a standard list.

As excessive pressure builds up in the storage tank or vessel the hinged hatch cover lifts, breaking the seal and allowing excess pressure to dissipate into the atmosphere. It closes under gravity when the pressure has returned to normal.

If the tank is subjected to negative pressure, the vacuum pallet and diaphragm assembly opens and allows air to be drawn into the vessel. The diaphragm closes when a positive pressure is established.

The unit must be installed on a flange at the top of the tank in the horizontal plane. It is possible to access the tank for gauging and sampling by fully opening the hatch.

Setting Range

Pressure & Vacuum : Weight-loaded +2.0 mbar and +60 mbar. (+0.8 inch W.C and +24 inch W.C)
Ambient temp : Weight-loaded -20°C to +60°C


Standard sizes : 2” to 12” 50 to 300mm
Flanges : API Class 150 RF, DIN PN16
Body : Carbon steel, stainless steel, or aluminium
Seals : Nitrile, Teflon, and Klingrit
Pallet : Stainless steel AISI 304
Weights : Carbon steel, stainless steel, or aluminium
Paint finish 1-) Powder Coating, Colour RAL 9006
2-) Epoxy Paint, Colour RAL 9006
3-) Customer Specification

Design & Manufacturing Specifications

The integrity of the seal is tested for leakage in accordance with API Standard 2521 - Use of Pressure-Vacuum Vent Valves for Atmospheric Loss.

The size of the vent should be calculated in accordance with API Standard 2000 (ISO 28300) - Venting Atmospheric and Low-Pressure Storage Tanks or other international standards.

Additional Information

Data sheet, Pressure Relief, Vacuum Relief, and Pressure-Vacuum Relief Valves

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