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The high-velocity relief valve (pressure/vacuum valve for cargo oil tank) generally uses by the relief system of the oil tanker and chemical tanker, according to the current regulations;IMO and IBC.
ISO15364: standards of Ships and Marine Technology Pressure/Vacuum Valve for Cargo Tank and the publication of the IMO. MSC/Circ.1009 Circular provide standards for designing, manufacturing, experimenting and maintaining the high-velocity relief valve.
Recently, Ship Design & Research Institutes and ship-owners ask for using the high-velocity relief valve which with high-quality, because the relief system used for oil tanker and chemical tanker is more important for the safety of the ship. It's not only for ensuring the safely of the cargo oil tank, avoid over-pressure or low-pressure; but also for controlling the fire, The dangerous of explosion and the releasing of the noxious gas. It also pays more attention on its practicability; provide the safest high-velocity relief valve with a good price.
ISO aseismatic marine high-velocity relief valve is the right product which meets to the above demands of ship Design & Research Institutes and ship-owners.
It changes the design method of the valve; make sure the valve is concerted sealed while it is closed. (Remark: the traditional high-velocity relief valve is in the contact seal while it is closed). The experiment proves the valve will open while the pressure of the system reaches to the set pressure; the valve stem is lifted or dropped while the pressure rising or falling. The stem will never full lifted and cracked while it under the maximum working pressure (less than 25kPa).
The valve will be never vibrated while the ship is moving, because the valve is concerted sealed while it is closed. It is the best choice to release the mixture gas of the tank.
The gravity type of the ISO high-velocity relief valve is its basic specification. It can reduce gravity and increase the magnetic force to make it becomes the gravity and magnetic type. The pressure differential will increases after the magnetic force is increased. Generally speaking, the Ship Design & Research Institutes and ship-owners will choose the traditional gravity type of the high-velocity relief valve for its safety.
When the liquid cargo ships need to load the goods of the propylene oxide class, with the DF-ISO high-velocity relief valve. The valve manufacturing materials for 304, 304L, 316L quality stainless steel, pressure valve opening pressure is generally set at 60KPa vacuum valve and the CF-ISO type is equivalent to the chart to below.
7.1 structure diagram of the DF-ISO high-velocity relief valve
7.2 selection and installation of the DF-ISO high-velocity relief valve
Generally used for liquid cargo ships, carrying propylene oxide class can load ordinary chemicals. Therefore, each cargo tank must be equipped with the CF-ISO, and DF-ISO high-velocity relief valve, and its installation method as shown below. When the loading of the ship propylene oxide class of goods, as long as the CF-ISO-pressure valve is forced to close can the contrary, such as the load of ordinary chemicals, simply open the forced shut-off device. Before loading and unloading shall be the operational requirements of the valve lift check. Inspection, you must also check the pressure valve and vacuum valve of the two valves, the role of mutual insurance, bucause the use of two of two valves can prevent the cargo hold overpressure and pressure loss. According to the flow range of the DF type pressure/vacuum valve can be installed in DN125(including DN125) following ventilation tube, the connection flange is optional by the user.
7.3 pressure curve of the DF-ISO high-velocity relief valve
7.4 types and main parameters of the DF-ISO high-velocity relief valve