Breather Valve Pressure testing Air Evacuation Valve emission calculation Evacuation Valve classification

Pressure testing: 1. Test preparation: The fire-retardant breathing valve should be properly installed on the test bench, the device should not leak, and the inner wall of the test tube should be smooth.

2. Detection medium: The test medium for the opening pressure, ventilation and leakage of the fire retardant breathing valve is air, whose absolute pressure is 0.1mpa, temperature is 20℃, relative humidity is 50% and density is 1.2kg/m3. If the air is not in this state, it should be converted into the gas in this state. The detection medium of the body pressure of the fire retardant breathing valve is 5-35 ℃ clean water.

3. Air pressure detection: First, test the leakage amount according to 4 (5) standard, and then test the sensitivity and ventilation rate according to 4 (3) and 4 (4) requirements.

4. Water pressure testing: The pressure of the fire retardant breathing valve for hydrostatic test is 0.2mpa, and the pressure holding time is 10min. The pressure test structure should meet the requirements of four (1).

5. Pressure detection: Will fire breathing valve installed on the air tank nozzle flange, regulating valve, make the rise and fall, the pressure inside the tank gradually adjust valve plate to make it in an open position, by connecting the micro pressure sensing pressure value on meter, read values once per minute, and then the valve disc rotate 90 °, 180 °, respectively, repeat the above test, the working condition of each repeated three times, take the average, The test results should meet the requirements of 4 (2) and 4 (3).

6. Leakage detection: The leak pressure is measured at 0.75 times the operating pressure, which is read from the micromanometer. The leakage value is read from the flowmeter (the accuracy of the flowmeter is level 0.5-1.0). Each measurement value is read once per minute, three times in total, and its average value is taken. The results shall meet the requirements of 4 (5).

7, Low temperature detection fire breathing valve fire breathing valve installed on the test rack into the low temperature box, low temperature box temperature.maintenance

Maintenance and maintenance of breathing valve once a month, twice a month in winter. Its method: first gently open the valve cover, take out the vacuum disc and pressure disc, check whether there is oil and dirt in the seal of the disc and the guide rod and guide rod sleeve of the disc, if there is oil and dirt should be cleaned, and then put back to the original position, pull up and down several times, check whether the opening is flexible and reliable. If all is well, then cover and tighten. In the maintenance and maintenance, if the valve disc is found to have scratches, wear and other abnormal phenomena, should be replaced immediately or contact with the supply company, in order to get timely solution.

Acceptance standard: API2000  SY/T 0511.1-2010 GB5908-86。

Operational emission calculation: Working emissions are losses due to artificial loading and unloading. As a result of charging, the pressure in the tank exceeds the release pressure, and the steam is pressed out of the tank; The discharge loss occurs when air is pumped into the tank at the liquid level and expands as it becomes an organic vapor-saturated gas, thus exceeding the capacity of the vapor space.

The working emissions of the fixed roof tank can be estimated by the following formula:

LW = 4.188 * 10 ^ 7 * M * KN * P KC

Where: LW- work loss of fixed top tank (Kg/m3 input)

KN- Turnover factor (dimensionless), whose value is determined by the annual turnover times (K). Turnover times = annual input/tank capacity

K<=36,KN=1

36 < K < = 220 KN = 11.467 x ^ 0.7026 K

K > 220 KN = 0.26

Respiratory emissions of fixed roof tanks can be estimated by the following formula:

LB (M = 0.191, P/(100910 - P)) ^ ^ 1.73 x 0.68 x D H ^ 0.51 x delta T ^ 0.45 * C * FP KC

Where: respiratory emissions of lB-fixed roof tank (Kg/a);

M- molecular weight of the vapor in the tank;

P- True vapor pressure (Pa) for a large number of liquids;

Diameter of d-tank (m);

H- Average steam space height (m);

△T- Average temperature difference within a day (℃);

Fp-coating factor (dimensionless), ranging from 1 to 1.5 according to paint condition;

C- Regulator for small diameter tanks (dimensionless); For tank with diameter between 0~9m, C=1-0.0123(D-9)^2; C=1 for tank diameter greater than 9m;

KC- Product factor (0.65 for petroleum crude oil KC, 1.0 for other organic liquids)

Classification: 1.tight type breathing valve: Tight type breathing valve is usually used in low pressure through pipeline, sealing performance completely depends on the fit between plug and plug body, the sealing surface of the sealing surface is achieved by tightening the nut at the bottom. Generally, PN≤0.6Mpa.

2.packing type breathing valve: Packing type breathing valve is by pressing the packing to realize the plug and plug body seal. Because of the packing, the sealing performance is good. Usually the breathing valve has a packing gland so that the plug does not extend out of the body, thus reducing the leakage path of one working medium. This breathing valve is widely used for pressure PN≤1Mpa.

3.self-sealing breathing valve: Self-sealing breathing valve is through the pressure of the medium itself to achieve close pressure between the plug and plug body. The small head of the plug extends out of the body upward, and the medium enters the big head of the plug through the small hole at the entrance, and presses the plug upward. This structure is generally used for air medium.

4.oil seal type breathing valve: Now the scope of application of breathing valve continues to expand, there is a forced lubrication of the oil seal type breathing valve. Forced lubrication forms an oil film between the sealing surface of the plug and the plug body. In this way, the sealing performance is better, the opening and closing force is saved, and the sealing surface is prevented from being damaged.

According to selected material: Cast iron breathing valve, carbon steel breathing valve, cast steel breathing valve, stainless steel (304, 304L, 316, 316L) breathing valve, aluminum alloy breathing valve, plastic (PVC, PP) breathing valve;

According to working principle: The first is to reach a certain pressure, breathe or suck; The other is designed purely to breathe without suction, which can be understood as two check valves with appropriate pressure instead. The second breathing valve is similar to the one-way check valve, it can only breathe out, can not breathe in, when the pressure in the system rises, the gas will be vent outward through the breathing valve, to ensure that the pressure of the system is constant. For the storage tank of toxic substances, there is no breathing valve, or breathing valve plus activated carbon filter and other treatment devices.

Breather valve is generally used in atmospheric pressure or low pressure storage tank, that is, only atmospheric pressure and low pressure storage tank can have tank breathing emissions (in the low pressure tank often steam recovery system), high pressure storage tank no emissions, no respiratory loss and work loss.

The main emissions of fixed top tank are divided into respiratory loss (small respiratory emissions) and work loss (large respiratory emissions).