Ultra-low discharge pressure

In the process of operation, especially in the start-up and shutdown of the air separation unit, one-way force should be avoided on the instrument. During the start-up of the equipment, close the high pressure and low pressure valves firstly, then open the balance valve, and then slowly open the high pressure (or low pressure) valve, so that the measured medium can enter the positive (negative) pressure chamber of the transmitter. If the liquid is to be measured, the gas in the positive (negative) pressure chamber should be discharged from the upper vent. If the gas is measured, drain the liquid accumulated in the positive (negative) pressure chamber from the lower drain screw hole. After discharging the gas (liquid), close the balance valve, and then open the valve on the other side. When the equipment is shut down, the high pressure (or low pressure) valve should be closed first, then the balance valve should be opened, and then the valve should be closed on the other side. Someti

Special pressure-bearing equipment generally bears internal pressure, that will cause tensile stress inside the shell, which is called working stress. The working stress is directly proportional to the pressure and diameter, and inversely proportional to the vessel wall thickness. The axial stress is half of the circumferential stress. Therefore, for cylindrical vessels, the stress of longitudinal weld is twice that of girth weld. Because the geometric shape of the spherical shell is symmetrical to the spherical center, and the axial stress is equal to the circumferential stress in numerical value. Therefore, the wall thickness of the spherical vessel can be reduced by half as much as that of the cylindrical vessel under the same pressure and diameter.