Air Operated Pinch Valve Enterprise Standard

1. Scope

This standard specifies the classification, requirements, test methods, test rules, markings, packaging, transportation, and storage of pneumatic pinch valves. This standard applies to air-operated pinch valves with flange or internal thread connection.

2. Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this document. For undated references, the latest version (including all amendments) applies to this document.

GB/T 1047 The definition and selection of DN (nominal size) of pipe components

The definition and selection of GB/T 1048 PN (nominal pressure) of piping components

GB/T 2828.1 Sampling Inspection Procedures by Attributes Part 1: Batch Inspection Sampling Plan Retrieved by Acceptance Quality Limit (AQL)

GB/T 2829 Attribute sampling procedures and tables for periodic inspection

GB/T 13277.1 Compressed air Part 1: Pollutant purification grade

GB/T 1 3927-2008 Industrial valve pressure test

3. Structure and Classification

3.1 Structure

The pneumatic pinch valve specified in this standard is a "straight-through" structure, consisting of five parts: control gas interface, valve body, gland, flexible rubber tube (hereinafter referred to as the inner bushing), and screws, as shown in Figure 1.

① Control gas interface

② Valve body

③ Gland

④ Flexible rubber tube (inner bushing)

⑤ Screw

Figure 1   Structure diagram of pneumatic pinch valve

3.2 Classification

3.2.1 Classification by connection method

The connection method can be based on the requirements of the agreement between the supplier and the demander, mainly as follows:

1) Flannel

2) Internal thread type

3.2.2 Classification by nominal size

The nominal size parameters of the pneumatic pinch valve should meet the requirements of GB/T 1047.

3. 2. 3 Classification by nominal pressure

The nominal pressure parameters of the pneumatic pinch valve should meet the requirements of GB/T 1047.

4. Working principle

When the control gas is not input in the pneumatic pinch valve, the cavity between the valve body and the inner liner is connected to the atmosphere, and the valve is in a smooth state, as shown in Figure 2. When the control gas enters the cavity between the valve body and the inner liner, the inner liner is compressed by increasing the pressure of the cavity. At this time, the valve is closed, and the powder particles reaching a certain size are closed by the elastic inner liner, and the valve is in the closed state, as shown in Figure 3.

A. Working pressure (delivery pressure)

Figure 2    State when the valve is open

A. Working pressure (delivery pressure)

B. Pressure difference

C. Set the optimal control pressure

Figure 3   State when the valve is closed

5. Technical requirements

5.1 General requirements

5.1.1 The pneumatic pinch valve shall be manufactured in accordance with the design drawings and process documents approved by the prescribed procedures.

5.1.2 The materials and purchased parts of the pneumatic pinch valve shall be re-inspected by the inspection department when entering the factory and shall comply with relevant standards.

5.2 Working environment

The working environment of the pneumatic pinch valve should meet the requirements of Table 1.

Table 1 Working environment of air operated pinch valve

5. 3 Appearance

5.3.1 The valve body should be painted, and the surface coating should be smooth and intact. There shall be no defects such as peeling, bruising, and marking. Fasteners must not be loose or damaged.

5.3.2  The surface of the inner bushing should be smooth and free of bubbles, pores, lack of glue, tearing, etc.

5.4 Valve body

5.4.1 Material The material of the valve body should be aluminum, stainless steel, or engineering plastics, or according to the agreement between the supplier and the buyer.

5. 4. 2 Dimensions

5.4.2.1 Flanged pneumatic pinch valve

The dimension diagram of the flanged pneumatic pinch valve is shown in Figure 4, and the dimension table is shown in Table 2.

Figure 4 The dimension diagram of the flanged pneumatic pinch valve

Table 2 The dimension table of the flanged pneumatic pinch valve

5.4.2.2  Internal threaded pneumatic pinch valve

The size diagram of the internally threaded pneumatic pinch valve is shown in Figure 5, and the size table is shown in Table 3.

Figure 5 The size diagram of the internally threaded pneumatic pinch valve

Table 3 The size table of the internally threaded pneumatic pinch valve

5.5 Inner bushing

5.5.1 The material of the inner liner should be wear-resistant natural rubber, natural rubber in the food industry, high-temperature resistant natural rubber, neoprene, nitrile rubber, butyl rubber or silicone rubber.

5.5.2 The service life should be greater than 100,000 to 300,000 times.

5.6 Control air source

It shall meet the requirements of GB/T 13277.1.

5. 7 Pressure

5.7.1 The maximum operating pressure (medium pressure) is 4 bar.

5.7.2 The normal control pressure (closing pressure) is 2.5 bar-4 bar.

5.7.3 The maximum control pressure (closing pressure) is 8 bar.

5. 7.4 The pressure difference between inside and outside is 2 bar-4 bar.

5.8 Tightness

According to 6.3 of GB/T 13927-2008.

6 Test method

6. 1 Appearance

Hand feel, visual inspection method inspection.

6.2 Materials

Test according to relevant standards.

6.3 Valve body

6.3.1 The dimensions and tolerances, structural length and wall thickness shall be inspected with measuring tools with corresponding accuracy requirements.

6.3.2 Other inspection methods requiring hand feel and visual inspection.

6.4 Inner bush

6.4.1 Use the program controller (PC) to control the solenoid valve to switch the control air source, thereby controlling the operation of the pneumatic pinch valve, and the program controller (PC) to record the number of operations, which should meet the requirements of 5.5.2.

6.4.2 Dimensions and tolerances, structural length, and wall thickness shall be inspected with measuring tools with corresponding accuracy requirements.

6.4.3 Other methods require hand feel and visual inspection.

6.5 Control air source

The inspection shall be carried out according to the provisions of GB/T 13277.1.

6.6 Pressure and tightness

Carry out inspection according to GB/T 13927.

7. Inspection Rules

7.1 Inspection classification

Product inspection is divided into factory inspection and type inspection

7.2 Factory inspection

7.2.1 Inspection items The factory inspection items shall be all the contents of 5.2, 5.4, and 5.8.

7. 2. 2 batch and sampling principles

7.2.2.1 The factory inspection items shall be carried out in accordance with the provisions of GB/T 28281.

7.2.2.2 Samples are randomly selected from the batch of products provided.

 7.2.3 Judgment rules

7.2.3.1 The acceptance quality limit (AQL) of the factory inspection items is 1.5.

7.2.3.2 After all the items required by the inspection institute are qualified, the batch of products is qualified. If one or more items are not qualified, the batch of products shall be determined as unqualified.

7.3 Type inspection

7.3.1 Inspection items

Type inspection of all items in the technical requirements of Chapter 5 of this standard.

7.3.2 Inspection conditions

Type inspection should be carried out in one of the following situations:

a) During trial production, finalization, and appraisal of new products;

b) When there are major changes in structure, materials, and processes;

c) During normal production. At least once a year;

d) When the product has been stopped for more than one year and resumed production;

e) When the factory inspection result is significantly different from the last type of inspection;

f) When requested by relevant state departments.

7.3.3 Sampling plan, sampling method, and determination rules

7.3.3.1 Sampling plan

A batch of 500 pieces of the same product, and a batch of fewer than 5,000 pieces, shall be carried out in accordance with the provisions of GB/T 2829, and a single sampling plan of discrimination level shall be adopted.

7.3.3.2 Sampling method

Samples are randomly selected from the qualified batches provided.

7.3.3.3 Judgment rules

Type inspection items are all items specified in this standard. If all inspection items are required to be qualified, the batch of products is qualified. If there are one or more unqualified items, double samples shall be taken from the same batch of products, and the unqualified items shall be re-inspected. If there are still unqualified items, the batch of products shall be determined as unqualified.