"Honeywell (Honeywell) Valve" stainless steel valve and the opening and closing parts are plug-shaped valve, seal appear before plane or cone, the fluid along the centerline of the disc in a straight line. Stem form of exercise with lifting rod (stem down, the hand wheel does not lift), but also lift rotating rod (with hand wheel and stem rotation movements, nut located in the body.) Valve is only applicable to fully open and fully closed, are not allowed to make adjustments and cut expenditure. Valve is forced closed valve, so valve is closed, the disc must exert pressure to force the sealing surface does not leak. When the medium into the valve from the valve below the six o'clock, the operating force required to overcome resistance, the stem and the packing of the friction force and the pressure generated by the media, the thrust force off the valve to open the valve than the force, Therefore, the diameter of the stem to a large, otherwise the top curved stem failure occurred. In recent years, the emergence of self-sealing valve, globe valve to change the media flow to the top of the valve into the valve chamber, when under pressure in the medium and close the valve of the force is small, and open the valve of the force, stem diameter can be reduced accordingly. Meanwhile, the role of the media, this form of valve is also more closely. China Valves "three to" have the provisions of the flow valve, all top-down. Valve is open, the valve opening height, the nominal diameter of 25% to 30%, the flow has reached the maximum that the valve has reached the fully open position. Therefore, valve fully open position, valve stroke should be determined. The classification of a valve. According to the channel direction valve is divided into: 1) straight-through valve 2) DC type valve: in the DC-type or Y-shaped valve, the valve body and the main channel flow into a slash This current state of the damage is smaller than the conventional cut-off valve, and thus the pressure loss through the valve correspondingly smaller. 3) Angle type valve: the angle-type valve, the fluid change only one direction, so that the pressure drop through the valve structure than conventional globe valves. 4) plunger type valve: This form of cut-off valve is a variant of conventional valves. In the valve, the valve disc and seat are usually designed based on the plunger principle. Polished into a valve stem is connected with the plunger, the plunger seal is on the two sets of elastomeric seals to achieve. Two elastic rings separated by a ring, and through the valve cover nut load exerted on the valve cover seals around the plunger pressure prison. Elastic ring can be replaced, you can use a variety of materials, the valve is mainly used for "open" or "off", but with a special form of plunger or special rings, can also be used to adjust flow. 2. According to the thread on the valve stem position can be divided into: 1) on the threaded stem valve: valve stem threads outside of the body. The advantage is that stem from media erosion, ease of lubrication, this structure uses more common. 2), thread stem valve: threaded valve stem in the valve body. This structure in direct contact with the media stem threads are vulnerable to erosion, and can not be lubricated. Such a structure for small-diameter and temperature is not high places. Valve has the following advantages: 1, simple structure, manufacture and maintenance more convenient. 2, the working stroke is small, open and close a short time. 3, sealing, and sealing surface between the friction force is small, longer life expectancy. Valve defects are as follows: 1, fluid resistance, force required to open and close more. 2, does not apply with particles, viscosity, easy to medium coke. 3, the regulation performance is poor. The type of valve stem according to the position of divided threaded male type, thread type. Divided by the flow medium, with straight-through, DC type and angle type. Divided by the form of valve seal, a packing seal bellows seal valves and stop valves. Cut-off valve structure: cut-off valve body structure in the form of straight-through, DC-and right-angle type. Straight-through is the most common structure, but its maximum fluid resistance. DC-type fluid resistance small, used for containing solid particles or viscosity of the fluid. Right Angle body to use more forging, for small circulation, high pressure cut-off valve. Valve installation and maintenance should note the following: 1, hand wheel, lever operated valves can be installed in any position in the pipeline. 2, hand wheels, handles and Wai actuator, does not allow for lifting purposes. 3, the medium flow direction of the arrow shown to be consistent with the body. The main valve Standard: 1, GB12233-89 "General Valve iron globe valves and lift check valve" 2, GB12235-89 "General Valve Flanged steel globe valves and lift check valve" 3, JB/T53174-94 "cut-off valve product quality grading" 4, JB/T53165-92 "pressure balance valve" 5, GB/T587-93 "Marine bronze flanged stop valve" 6, GB/T590-93 "ship with cast iron flanged stop valves "7, GB8464-87" thread connecting valve, globe valve, ball valve, check valve, the basic size, iron valve "8, GB8465.2-87" thread connecting valve, globe valve, ball valve, check valve basic valve dimensions iron "