Compare the diaphragm valve and bellows valve in aseptic process equipment, globe valve, diaphragm valve, ball valve, gate valve, safety valve and other valves how to test pressure, what are the methods?

Compare the diaphragm valve and bellows valve in aseptic process equipment, globe valve, diaphragm valve, ball valve, gate valve, safety valve and other valves how to test pressure, what are the methods?

In aseptic production process, the commonly used stop valve is diaphragm stop valve, usually referred to as diaphragm valve. The reason why diaphragm valves are used in aseptic production processes is because of their simple structure and low price, which makes it so far there are few “competitors”. Competing with diaphragm valves are so-called bellows globe valves, commonly known as bellows valves. This bellows globe valve because of its high price, although it has a better technical advantage than the diaphragm valve, but it is still difficult to compete with the diaphragm valve, as described in this article.

PTFE corrugated tube

The competition between bellows and diaphragms has a long history in the aseptic process industry. For a long time, diaphragm valve with its simple structure, low price and clean disinfection and convenient to occupy the upper hand. Compared with diaphragm valve, bellows valve in the market variety specifications are too few. Vesta bellows valve produced by Tuchenhagen is just to fill this gap, this paper through the diaphragm valve and bellows valve comparison, the advantages and disadvantages of the two valves are more clear.

Empty out function

When you need to use the diaphragm valve in the horizontal pipeline, you must ensure that the diaphragm valve is installed in the horizontal pipeline according to the Angle defined by the diaphragm valve manufacturer. Otherwise, in the operation of the process equipment, the clearance of the diaphragm valve will encounter some problems, and the medium in the valve body can not be completely discharged. However, the installation tilt Angle of different diaphragm valve types, diaphragm valves produced by different manufacturers and diaphragm valves with different nominal flow rates is different, which often brings great trouble to the design and manufacture of aseptic process equipment. In T – shaped diaphragm valves, this empty-body problem is more pronounced.

Compared with diaphragm valve, Vesta bellow valve will not cause such a problem, no matter what kind of structure of the Vesta bellow valve body is, in the process of equipment no-load operation will not be a “dead Angle”, so as to ensure a tight partition of the pipeline. Furthermore, it can be installed in the ductwork of aseptic process equipment in different installation modes.

In the pharmaceutical manufacturing industry, aseptic process equipment consists of many horizontal and vertical pipes. In the design of pharmaceutical equipment, because of the pipe location and technical reasons, it is necessary to install the bellows valve in a specific location. For example, if a diaphragm valve is installed in a vertical pipe, it must be connected by a 90° bend in a uniform horizontal plane. The production cost of T type diaphragm valve is very high, compared with different valve body structure shape diaphragm valve, bellows valve is in volume and shape, and the connection with the pipe installation more upper hand. Because the two types of globe valves are different in structure, therefore, in the early design of aseptic process equipment, we should choose which type of globe valve should be selected for each part.

Output devices in the fields of medicine, food and biotechnology have a large number of valves that need to be sterilized. Large valves, such as those of the Stericom series, are of little use in situations where disinfection is required. Because, in these process equipment, the transmission requirements of the medium quality is less and less, for less flow, people almost no one outside the choice of diaphragm valve. The new bellows valve has a smaller size and can be used with different pipe diameters, which gives it an advantage over diaphragm valves.

Comparison of equipment utilization

As the user of the equipment, in the whole life cycle of the equipment as much as possible to use the equipment for production, that is to say: the utilization rate of the equipment should be as high as possible. The maintenance of the equipment means that the equipment must stop production, but also put in a certain amount of equipment maintenance. Bellows valve generally have wear phenomenon; In the diaphragm valve, once the valve is worn, the diaphragm must be replaced after a certain use time. The service life of the diaphragm depends on the corresponding production process. On the one hand, the erosion of smooth media in the process equipment, the temperature of pipeline cleaning and disinfection, the working pressure and flow rate of the process equipment and other working parameters will affect the service life of the diaphragm; On the other hand, the deformation of the diaphragm when the diaphragm stop valve is opened and closed is also an important factor to determine the service life of the diaphragm.

Vesta bellows stop valve with pneumatic drive

Most diaphragm valve damage is not due to use in the production process, on the contrary, due to mechanical extrusion damage. Although diaphragm valves have different elastic levels, different coatings, and different PTFE plates, but for all diaphragm valves have from the outside invisible wear (surface erosion and particle attachment caused by internal media). Therefore, in order to avoid aseptic process production due to damage to the diaphragm valve forced to stop production, in practice is usually in the delimited service life before the replacement of the diaphragm. In this way, whether it is forced to replace the number of diaphragms, is still the resulting maintenance, or equipment downtime, are significantly more than PTFE bellows valve, and another advantage of bellows valve is that it can be used for almost a variety of processes.

parts

The hub component of Vesta bellows valve is TFM1705PTFE cutobellows. In addition to being resistant to the corrosion of various chemical media, TFM1705 materials also meet the requirements of FDA Section 21 §177.1550 of the Federal Regulations for “perfluorocarbon resin”. Its smooth surface (Ra≤0.8mm), reliable seal, large switch motion interval and other characteristics, for a better CIP/SIP disinfection and cleaning are often favorable. For more than three years, the patented bellows valve has been successfully established in the market and provides strict isolation of the atmosphere inside and outside the pipe in a sterile process pipe.

Globe valve, diaphragm valve, ball valve, gate valve, safety valve and other valves how to test the pressure, what are the methods?

In the industry production, water pump installation valve is commonly used equipment, before the use of the valve, some need to test pressure, for globe valve, diaphragm valve, ball valve, gate valve, safety valve and so on, what are the pressure test methods of the valve, under normal circumstances, industrial valves in use do not do strength test, but after repair valve body and valve cover or erosion damage valve and valve cover should do strength test. For safety valves, the setting pressure and return pressure and other tests shall conform to the specification of their copy and related regulations. Strength and tightness tests should be conducted before valve installation. Low-pressure valve spot check 20%, such as the division should be 100% inspection; Medium and high pressure valves should be checked 100%. The commonly used medium of valve pressure test is water, oil, air, steam, nitrogen, etc. The pressure test method of various industrial valves including pneumatic valves is as follows:

1. Pressure test method of globe valve and throttle valve

The strength test of the globe valve and throttle valve, usually put the assembled valve in the pressure test frame, open the valve disc, inject the medium to the specified value, check whether the valve body and valve cover sweat and leakage. Can also be a single piece of strength test. The sealing test is only for the stop valve. Test the stop valve stem into a vertical state, valve disc open, the medium from the bottom end of the disc into the delimited value, check the packing and gasket; When qualified, close the disc and open the other end to check whether there is leakage. If the valve strength and sealing test are to be done, you can do the strength test first, and then step-down to the sealing test delimited value, check the packing and gasket; Then close the disc, open the outlet to check whether the sealing surface leakage.

2. Pressure test method of gate valve: The strength test of gate valve is the same as that of globe valve. There are two ways to test the tightness of gate valves.

① The gate is opened so that the pressure inside the valve rises to the specified value; Then close the gate, immediately take out the gate valve, check whether there is leakage in the seal on both sides of the gate, or directly inject the test medium into the plug on the valve cover to the specified value, check the seal on both sides of the gate. The above method is called intermediate pressure test. This method is not suitable for the seal test of gate valve with nominal diameter DN32mm.

(2) The other way is to open the gate, so that the test pressure of the valve rises to the specified value; Then close the gate, open one end of the blind plate, check whether the sealing surface leakage. Repeat the above test until qualified.

The tightness test at packing and gasket of pneumatic gate valve shall be conducted before the tightness test of gate valve.

3, butterfly valve pressure test method

The strength test of pneumatic butterfly valve is the same as that of globe valve. The sealing function of the butterfly valve should be tested from the human end of the medium flow into the test medium, the butterfly plate should be opened, the other end of the blockade, injection pressure to the specified value; After checking the packing and other seals for no leakage, close the butterfly plate, open the other end, and check the butterfly plate seal for no leakage. The butterfly valve used for regulating the flow does not do the sealing function test.

4. Pressure test method of plug valve

Before the test of the plug valve, a layer of non-acidic dilute lubricating oil is allowed on the sealing surface, and no leakage and expanded water droplets are found within the specified time as qualified. The test time of the plug valve can be shorter, generally defined as l ~ 3min according to the nominal diameter.

(1) When the plug valve is tested for strength, the medium is introduced from one end to block the rest of the way, and the plug is rotated to the fully open working position in turn for test. No leakage is found in the valve body.

(2) In the sealing test, the longitudinal cock should keep the pressure in the cavity equal to that of the passage, rotate the plug to the closed position, check from the other end, and then rotate the plug 180 times to repeat the above test; Three-way or four-way plug valves should keep the pressure in the chamber equal to that at one end of the passage, rotate the plug to the closed position in turn, introduce the pressure from the right Angle end, and check from the other end at the same time.

5. Pressure test method of check valve

Check valve test state: lift type check valve disc axis in a horizontal and vertical position; Swing check valve channel axis and disc axis are approximately parallel to the horizontal line. During the strength test, the test medium is introduced to the defined value from the inlet end, and the other end is blocked. It is qualified to see that the valve body and valve cover have no leakage. The sealing test shall introduce the test medium from the outlet end, and check the sealing surface at the entrance end. It is qualified that there is no leakage at the packing and gasket.

6, the pressure test method of safety valve

The strength test of the safety valve is the same as that of other valves, which is tested with water. When testing the lower part of the valve body, the pressure is introduced from the inlet I=I end, and the sealing surface is sealed; When testing body top and bonnet, pressure is introduced from the exit El end and other ends are blocked. The valve body and bonnet shall be qualified without leakage within the specified time.

(2) Tightness test and constant pressure test, the general use of medium is: steam safety valve with saturated steam as the test medium; Ammonia or other gas valve with air as the test medium; The valve for water and other non-invasive liquids uses water as the test medium. Nitrogen is commonly used as the test medium for some important safety valves.

Seal test with nominal pressure value as the test pressure test, the number of times is not less than two times, no leakage within the defined time is qualified. There are two kinds of leakage detection methods: one is to seal the connection of the safety valve, and paste the tissue paper with butter on the El flange. The tissue paper is bulging for leakage, not bulging for qualified; The second is to use butter to seal the thin plastic plate or other plates on the lower part of the outlet flange, water seal the valve disc, check the water is not bubbling qualified. The constant pressure and return pressure test times of the safety valve shall be no less than 3 times, and shall be classified as qualified. Safety valve function test see GB/T122421989 safety valve function test method.

7. Pressure test method of pressure reducing valve

(1) The strength test of the pressure reducing valve is generally assembled after a single test, or after assembly test. Strength test duration: DN50mm lmin; Dn65-150mm longer than 2min; DN150mm longer than 3 minutes. After the bellows are welded with the components, the strength test is carried out with air at 1.5 times the high pressure after the pressure reducing valve is applied.

② The tightness test is carried out according to the actual working medium. When testing with air or water, the test shall be conducted at 1.1 times the nominal pressure; The steam test is carried out at the relatively high working pressure allowed at the operating temperature. The difference between the inlet pressure and the outlet pressure should be no less than 0.2MPa. The test method is as follows: after the inlet pressure is adjusted, the adjusting screw of the valve is gradually adjusted, so that the outlet pressure can change rapidly and continuously within the large and small value range, without stagnation and blocking phenomenon. For the steam pressure reducing valve, when the inlet pressure is removed, the valve is closed and then the valve is truncated, and the outlet pressure is high and low. Within 2min, the appreciation of the outlet pressure should be in line with the value specified in Table 4.17622. Meanwhile, the pipeline volume behind the valve is defined as qualified in line with Table 4.18. For water and air pressure reducing valves, when the inlet pressure is set and the outlet pressure is zero, the sealing test is carried out on the closed pressure reducing valve. It is qualified that there is no leakage within 2 minutes.

8, ball valve pressure test method: pneumatic ball valve strength test should be carried out in the ball half open state.

① Floating ball valve tightness test: the valve is half open, one end into the test medium, the other end blocked; The ball will roll several times, the valve is closed when opening the sealing end inspection, at the same time check the packing and gasket sealing function, there should be no leakage phenomenon. Then the test medium is introduced from the other end and the above test is repeated.

(2) Fixed ball valve tightness test: before the test the ball will be no-load rolling several times, the fixed ball valve is in a closed state, from one end of the test medium to the delimited value; The pressure gauge is used to check the sealing function of the inlet end. The accuracy of the pressure gauge is 0.5 ~ 1, and the measuring range is 1.5 times of the test pressure. At the time of demarcation, no depressurization phenomenon is qualified; Then introduce the test medium from the other end and repeat the above test. Then, the valve is half open, the two ends are blocked, the inner cavity is filled with medium, check the packing and gasket under the test pressure, there should be no leakage.

③ Three-way ball valve should be long in each position for sealing test.

9, diaphragm valve pressure test method

Diaphragm valve strength test from either end of the introduction of the medium, open the disc, the other end of the blockade, test pressure to the specified value, see the valve body and valve cover no leakage is qualified. Then step down to the tightness test pressure, close the disc, open the other end for inspection, no leakage is qualified.