Hydrostatic Testing on standard Tank size is $35.00 - With VE stamp $70.00 - Larger cylinders then standard scuba $80.00+. Hydros includes the Visual inspection, tank washed out, and air fill.
In accordance with regulations specified by Transport Canada and in the United States by the Department of Transport (D.O.T.) certain cylinders must be periodically re-qualified and certified safe for use.
The re-qualification procedures and regulations are discussed in detail in Canada's Code of federal regulations (CFR). Transport Canada manual code B339 and B340. U.S. Code of federal regulation (CFR) Department of Transportation title 49, section 173.34.
All Co2 tanks 12oz. or greater, and all High Pressure tanks used for the sport of Paintball, require by Federal Law, to be Hydrostatically tested. With NO exceptions.
The specifications and procedures for Hydrostatic testing methods are also outlined in Compressed Gas Association Pamphlet C-1, "Methods for Hydrostatic Testing of Compressed Gas Cylinders".
The water jacket method for Hydrostatic testing consists of loading a water filled cylinder into a sealed chamber (test jacket), which is also filled with water and is connected to a calibrated glass tube (burette) or Galiso's patented Electronic Expansion Measuring System (Expansion Bowl) in place of the burette. The burette or Expansion Bowl is first zeroed, and the cylinder is then pressurized to its test pressure (typically 5/3 of it's D.O.T. or I.C.C. rating). This test pressure is held for a minimum of thirty seconds.
As pressure is applied to "inflate" the cylinder, the cylinder expands and forces water out of the test jacket and up into the burette or Expansion Bowl. After the test hold time has elapsed, the burette or Expansion Bowl is then read to determine the Total Expansion (in cubic centimeters) of the cylinder under test pressure. The test pressure is released and the cylinder "deflates". As the cylinder shrinks to it's approximate original size, water flows back into the test jacket from the burette or Expansion Bowl. In most cases, the cylinder will not return to it's original size, having been slightly stretched by the pressurization process, and a portion of the expansion water remains in the burette or Expansion Bowl. This stretching is called the Permanent Expansion. The difference between the Total Expansion and the Permanent Expansion is called the Elastic Expansion. The Percent Permanent Expansion of the cylinder is determined by the following formula:
Percent Permanent Expansion = (Permanent Expansion / Total Expansion) X 100
When the Percent Permanent Expansion exceeds the predetermined limits for the cylinder being tested, the cylinder must be condemned and removed from service. A high Percent Permanent Expansion value is an indication that the cylinder metal has lost it's ductility, or that there has been excessive thinning of the cylinder wall and that the cylinder is no longer safe for use. Test pressures and retest intervals can be found in the table following paragraph (e) of 173.34.
All records of visual inspection and Hydrostatic retest must be maintained until either the expiration of the retest period or until the cylinder is again reinspected or retested, whichever occurs first.
Plus (+) stamped cylinders, in certain gas services, may be filled to an additional 10 percent beyond the rating which is stamped on the cylinder shoulder. Star (*) stamping makes the cylinder eligible for an extended ten year re-test interval. The Water Jacket Method of testing compressed gas cylinders is the only Hydrostatic test method that qualifies cylinders for filling to 10% over service pressure.
The procedures and requirements are found in 49 CFR 173.302(c) for plus stamping, and 173.34(e)(16) for the star. REE values for common cylinders can be found in Compressed Gas Association Pamphlet C-5, "Cylinder Service Life, Seamless High Pressure Cylinders".
During the direct expansion test, the cylinder is completely filled with water and the test connection is then screwed into the cylinder neck. Water is pumped into the cylinder until the desired test pressure is achieved. (Test pressure requirements are contained in the
U.S. Code of Federal Regulations, 49CFR173.34.)
The volume of water which must be pumped into the cylinder to reach the test pressure is measured to determine the Total Expansion. The volume of water that is expelled from the cylinder when pressure is released is measured to determine the Permanent Expansion.
Because air has a different compressibility factor than water, air trapped inside the cylinder will cause inaccurate test results. So, it is very important that the cylinder is completely filled with water to eliminate trapped pockets of air. The weight of the water contained in the cylinder, the test pressure, test volume(s) and the compressibility factor are then used to determine the required expansion values.
Transport Canada, DOT Regulations require the Water Jacket Method to be used when qualifying cylinders for filling to 10% over service pressure and therefore forbid the Direct Expansion test method to be used to re-qualify cylinders for the plus ("+") stamp. The Direct Expansion test method is discussed in detail and example calculations given in CGA pamphlet C-1, "Methods for Hydrostatic Testing of Compressed Gas Cylinders".
The U.S. Code of Federal Regulations 49 CFR 173.34(e)(10) and (11) allows certain specified cylinders only, which are used exclusively in the service specified to be requalified without determining the total and permanent expansions. For such cylinders, the Proof Pressure method may be used.
The Proof Pressure Test involves pressurizing a cylinder to the appropriate test pressure (without the use of a water jacket) and then thoroughly inspecting the cylinder, while under pressure, for leaks, deformations or any indication of defects. When re-qualified by this method, the requalification period is typically shortened, and an "S" is added following the test date marking to indicate the "modified" hydrostatic test.
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