The safety attachment of the pressure vessel is an attachment that is installed to allow the container to operate safely. Usually, not only devices that can automatically relieve pressure are called auxiliary devices, such as safety valves, rupture disks, etc., but also some safety-related parameter measuring instruments in display devices, such as pressure gauges and liquid level gauges. As a safety accessory, these devices allow the operator to keep abreast of the operation of the equipment and find unsafe factors in order to take measures to prevent accidents.
Common safety accessories for pressure vessels are pressure gauges, liquid level gauges and safety relief devices.
A pressure gauge is a meter used to measure the pressure of a medium in a container. In pressure vessels, most use spring tube pressure gauges. Special pressure gauges should be used on high pressure gas cylinders such as oxygen cylinders and acetylene cylinders, and membrane pressure gauges are also used in some corrosive containers for working media. A U-type pressure gauge is used on the low pressure vessel.
First, the liquid level meter
The liquid level gauge is only used on individual pressure vessels, such as flammable or highly toxic, toxic medium liquefied gas containers, device plate glass level gauges or automatic liquid level indicators. There should be a leak prevention device and a protective cover on the level gauge or level indicator.
Some containers need to control the temperature, and must be equipped with temperature measurement or automatic temperature control instrument to prevent over temperature.
These are safety accessories that ensure the safe operation of pressure vessels and should be checked regularly to ensure their accuracy and safety.
Second, the safety pressure relief device
(1) The function of the safety relief device and its setting principle
The pressure vessel is designed according to the predetermined service pressure. Its wall thickness can only be subjected to a certain pressure, the so-called maximum service pressure. In this range, the inner container can operate safely. Above this pressure, the container may be damaged. For various reasons, pressure vessels often experience overpressure during operation. If the pressure comes from the pressure vessel outside the container, when the intake air volume is greater than the output gas volume, the negative gas density increases and the pressure rises; the pressure relief valve fails or the operation error occurs, and the high pressure gas directly enters the container to cause overpressure; Or the temperature rises, the liquid in the device expands, the pressure increases sharply; the chemical reaction of the medium in the container increases the pressure and so on.
1. The role of safety relief device
The safety relief device is a safety device that prevents overpressure and ensures safe operation of the pressure vessel. When the container is working under normal pressure, it remains sealed and leaks. When the pressure of the container exceeds the specified level, the gas in the container can be quickly discharged, so that the pressure inside the container is always within the maximum allowable pressure range. It not only has this main function, but also an alarm job. When the exhaust gas is opened, the gas flow rate is high, and a large sound can be generated, which becomes an overpressure alarm signal.
2. Setting principle of safety relief device
(1) In a continuously operated system, such as a plurality of pressure vessels with the same working pressure, and the gas pressure does not rise by itself in each container, it may be installed on the connecting pipe or one of the containers according to the same pressure system. Set a safety relief valve.
(2) The pressure in the pressure vessel is caused by the chemical reaction of the medium in the vessel, or the chemical reaction can increase the pressure. A safety relief device should be installed separately.
(3) The pressure of the medium in the pressure vessel will increase due to the heat inside and outside the vessel, and if the connecting pipeline between the vessel and other equipment is equipped with a valve, a safety relief device should be installed separately.
(4) For pressure vessels that use glaze or use steam, if the maximum allowable pressure is not less than that of a steam boiler, a safety relief device may not be installed. If the steam is fed into the pressure vessel after passing through the pressure reducing valve and the maximum allowable pressure of the steam is less than the boiler, a safety relief device should be installed on the vessel or on the pressure reducing valve outlet pipe.
