Among a wide variety of oil and gas equipment used in a particular area of industrial activity, the most significant media attention to breathing.One of the brightest representatives of such agents are neprimerzayuschie mechanical breathing valve (hereinafter - NDKM).NDKM - a mechanical device that provides complete sealing vnutrirezervuarnogo space, as well as regulation, within the previously set technical parameters, the pressure within the appropriate tank (reservoir), formed due to the evaporation of petroleum products.The main difference between the valves NDKM from other devices with similar functional elements - a strict application only on light fractions of petroleum products such as gasoline of any octane, kerosene, etc.
structure NDKM consists of five main types (NDKM-350 NDKM-250 NDKM-200 NDKM-150 and NDKM 100) differ in nominal diameter, the amount of pressure and vacuum operation, conditional capacity and structural dimensions.In addition, depending on climatic factors that will directly affect the NDKM during their operation in a certain macro-regions, as valves can be divided into devices with elements designed for operation in areas with a temperate climate (from +40 to -45degrees Celsius), and on the device with elements designed for operation in areas with moderate-cold climate (from +40 to -60 degrees Celsius).
Regardless of the choice of the appropriate type NDKM, their structure is identical and includes:
- upper body,
- lower body,
- membrane lower assembly,
- upper diaphragm,
- fungus,
- flame arrester,
- housing,
- cover,
- adapter.
principle of operation.In the formation of a vacuum in the tank (reservoir) between the lower and upper diaphragm membrane of a vacuum, with a notional value equal to the vacuum in the space of the gas-tank (reservoir).Upon reaching a vacuum pressure lower than the calculated values, the difference is the weight of the membrane forces and pressure forces air at its surface causes the lower membrane begins to seat tightly against the lower housing.At the time of exceeding the calculated values of the power vacuum to a pressure of air on the bottom surface of the membrane exceeds the weight of the membrane, thus moving it up and connecting the gas-air space capacity (tank) to atmospheric.At the time of reducing the quantities of vacuum lower than estimated, the bottom membrane is lowered onto the saddle, thus sealing capacity (rezervar).
The formation in the tank (reservoir) pressure differential between the lower and upper diaphragm membrane creates a pressure equivalent to the level of pressure in the gas-air space of the container (tank).With increasing pressure force under the action of which the bottom membrane is adjacent to the seat increases, thereby improving the tightness of the shutter and acting simultaneously on the upper diaphragm disc and a load connected by means of a flexible connection with the lower membrane.Thus, the pressure acts on the diaphragm and the top and bottom, reducing the total membrane area in comparison with the area of the diaphragm.This difference raises the diaphragm area up, and with it and the membrane, resulting in a Post-gas space capacity (tank) to the atmosphere.
Safety Precautions When using this type of device involve:
- a ban on the opening of the period of operation of an industrial complex in which the valve is mounted;
- location of staff at the time of disassembly (maintenance) should not be on the windy side;
- the use of repair kits is allowed only one brand, which is the valve itself;
- mandatory use of only intrinsically safe instruments.
NDKM Average duration of work (subject to the instructions for use and maintenance) of 20,000 cycles of opening / closing of the valve, or 10 years.
