Automatic return valve principle and installation specifications The valve installed in the boiler feed pump outlet, to prevent water backflow, and to ensure that there is a certain minimum recycle bypass flow. Second, the structural characteristics and working principle: The three-way valve to the pump by the valve body and valve cover connected through the flange, in order to facilitate the installation, maintenance and repair of seat grinding, changing the original one-piece structure. Valve seat and the valve are hard alloy surfacing to ensure that the erosion, wear and sealing, extending the service life. Body seal for the rubber seal seal to ensure the reliability of the seal. Valve body import and export and recycling system exports are flanged, easy disassembly and maintenance. This valve sets the components in one, to complete four different functions: 1. Although installed at the outlet of the pump, it automatically detects the size of the pump flow and actuates the recirculation control valve via the pilot valve (instead of the indirect pressure-controlled recirculation action). 2. The valve body is equipped with recirculation decompression facilities, which can make the high-pressure medium flow around the small diameter several times and consume a large amount of energy to reduce the pressure of the recirculation system. 3. This valve only recirculates to cool the pump when the flow rate is very low. When the pump is in normal operation, it does not recirculate, thus saving the energy and water energy consumed by continuous recirculation in the past. 4. This automatic recirculation control valve does not require electrical wiring and does not require two regulating valves in series (one for regulation and one for shut-off) and minimizes high-speed flow cords and erosion easily created by high pressure systems. The working principle of the main valve to reduce flow, the main valve flap in the direction of the spring force to move to the seat, when the flow through the pump to reach the minimum flow, the valve flap guide rod driven to reduce the pressure on the piston, The piston moves to open the bypass valve (the fluid through the bypass valve is depressurized by the bypass flap), allowing for a small amount of recirculation of the pump during low-load operation, ensuring pump cooling. When the flow rate exceeds the pump minimum flow, the main valve flap up, so that the pilot valve is closed, cut off bypass. From the fundamental solution to the previous system is not running smoothly, noise, short life expectancy, expensive, installation and maintenance inconvenience shortcomings. Installation, maintenance and use precautions 1. Has completed the test, after passing the test valve has been assembled and debugged, users do not need to dismantle, can be installed directly. 2. Transport hoisting process carefully, to avoid bruising. 3. When installing the valve, the direction of the flow of the medium should be the same as the direction of the arrow shown on the valve. 4. Valve should be stored in a dry place, not open storage, the valve should be blocked when the channel port to prevent debris fall into. Stock must be regularly maintained to prevent corrosion.
Cutting Torches
CUTTING TORCHES
The equipment and accessories for oxygas cutting are the same as for oxygas welding except that you use a cutting torch or a cutting attachment instead of a welding torch. The main difference between the cutting torch and the welding torch is that the cutting torch has an additional tube for high-pressure cutting oxygen. The flow of high-pressure oxygen is controlled from a valve on the handle of the cutting torch. In the standard cutting torch, the valve may be in the form of a trigger assembly like the one in figure 4-11. On most torches, the cutting oxygen mechanism is designed so the cutting oxygen can be turned on gradually. The gradual opening of the cutting oxygen valve is particularly helpful in operations, such as hole piercing and rivet cutting.
Figure 4-11.-One piece oxygas cutting torch.
Torch Body
Most welding torches are designed so the body of the torch can accept either welding tips or a cutting attachment. This type of torch is called a combination torch. The advantage of this type of torch is the ease in changing from the welding mode to the cutting mode. There is no need to disconnect the hoses; you just unscrew the welding tip and then screw on the cutting attachment. The high-pressure cutting oxygen is controlled by a lever on the torch handle, as shown in figure 4-12.
Figure 4-12.-Cutting attachment for combination torch.
Cutting Torches,Gas Cutting Torch,Plasma Cutting Torch,Air Cooled Cutting Torch
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