Spray Paint Equipment

Spray booth function and classification

The most basic task of the spray booth is to remove the paint mist, paint dust, solvent, etc. from the spraying process.

The spray booth system equipment generally consists of a spray booth chamber, a supply air system, a paint mist trapping device, a circulating water system, an exhaust system, and a waste paint removing device.

Paint mist is sprayed paint particles, which are not yet dry and remain adhesive; paint dust is sprayed paint particles that are powdery and lose adhesion as the solvent evaporates, float in the paint booth, then adhere to the product and becomes one of the reasons for poor coating.

The spray paint booth should have the following two functions:

Purpose:

1. Ensure the safety of the painting site;

2. Prevent the attachment of garbage;

3. Paint and paint mist do not pollute the surrounding environment;

4. Discharge the accumulated solvent evaporation in time.

Features:

1. Exhaust: exhaust and discharge paint mist;

2. Dust removal: remove paint (dust) from the discharged air

3. Supply air: supply clean air;

4. Illumination: Install an explosion-proof lamp to illuminate the surface of the object to be coated.

Painting System Technical Conditions

1 Scope.............................................1

2 Normative references..............................1

3 Terms and definitions....................................1

4 Technical requirements..........................................1

4.1 Paint supply method....................................1

4.2 Paint supply pressure....................................2

4.3 Technology for paint supply system..............................2

4.4 Paint circulation system..............................2

4.5 Basic requirements of the paint circulation system..................2

4.6 Composition of the paint circulation system........................3

4.7 Cleaning and testing of paint circulation system............5

4.8 Use and management of paint recycling system............6

4.9 Automatic color change....................................6

5 Safety, environment and health..............................7

6 Inspection items and methods..............................7

6.1 Inspection of main design parameters........................7

6.2 Inspection of the structure and key parts of the system.........7

6.3 System leak test....................................7

6.4 System commissioning....................................7

6.5 Others..........................................7

Table 1 Pressure requirements of the paint circulation system..................3

Table 2 Paint circulation system flow requirements..................3

Table 3 Coating circulation system flow rate requirements..................3

Table 4 Pipe support distance..............................5

Painting System Technical Conditions

1 Scope

This standard specifies the technical requirements for the paint supply system for liquid coatings.

This standard applies to the paint supply system and its components in the paint factory or paint shop.

Where there is no special requirement in the product drawings, technical documents or order contracts of the paint supply system and its components, it shall comply with the provisions of this standard.

2 Normative references

The terms in the following documents become the terms of this standard by reference to this standard. All dated references, all subsequent modifications (not including errata content) or revisions do not apply to this standard, however, parties to agreements based on this standard are encouraged to study the possiblity to use the latest version of these files. For undated references, the latest edition applies to this standard.

GB /T 2 3 51-1993 Hard tube outer diameter and hose inner diameter for hydraulic and pneumatic systems

GB 6 5 14 Safety rules for painting operations Paint process safety and ventilation purification

GB 7 6 91 Safety rules for safety procedures for painting operations

GB /T 8 2 64 Coating technical terminology

ISO 8 43 4: 1995 Metal pipe joints for fluid transfer and general use

3 Terms and definitions

The following terms and definitions established in GB/T 8 2 64 apply to this standard.

3.1

Spray tool

Refers to painting tools such as spray guns, rotating cups, and rotating discs during painting.

3.2

coatingc ycles ystem

Coating circulation system

It is a pipeline network that uses a pressure pump to deliver paint liquid to the spray station at a certain pressure and flow rate, and can control the properties of the paint liquid.

4 Technical requirements

The paint supply system shall be capable of providing a continuous, uniform pressure, pressure-adjustable flow to the spray. The paint supply system itself shall comply with the relevant fire, explosion and antistatic regulations.

4.1 Paint method

Common paint delivery systems are available in siphon, gravity and pressure.

4.1.1 Siphonic

Siphon-type paint supply usually puts the paint container under the sprayer, and relies on the negative pressure generated by the liquid or gas in the siphon pipe above the container to form a siphon effect to suck out the paint liquid in the container, thereby realizing the supply of the spray gun. paint.

4.1.2 Gravity

Gravity paint supply is to place the container of paint on top of the sprayer, and rely on the gravity of the paint itself to supply paint to the lower sprayer.

4.1.3 Pressure type

Pressure paint supply relies on compressed air or a pressure pump to pressurize the paint liquid and transport it to the spray gun. The pressure type paint can provide the paint liquid with high pressure and large flow rate, and can realize long-distance transportation of high-cat material and medium-scale centralized transportation. The circulating paint supply system is the most important paint supply system in the pressure centralized paint supply system.

4.2 Paint supply pressure

According to the paint supply pressure, the paint supply system can be divided into normal pressure, low pressure, medium pressure and high pressure.

4.2 .1 atmospheric pressure

Paint system pressure - <O.1MPa, such as siphon, gravity paint and some specific requirements for pressure paint.

4.2 .2 low pressure

O.1 MP a< The pressure of the paint supply system < 1.6MPa, which is common in flow coating systems for flow coating, roller coating and medium and small air spraying.

4.2.3 Medium voltage

1.6M P a< The pressure of the paint supply system< 10MPa, common in medium to large air spray centralized paint supply system and air-assisted spray paint supply system.

4.2.4 High pressure

The paint supply system pressure is > 10MPa, which is common in high-degree materials or airless sprayed centralized paint supply systems.

4.3 Technical requirements for paint supply systems

4.3.1 The rated pressure of all components in the paint supply system shall not be lower than the maximum working pressure of the system part where it is located.

4.3.2 The size of the hard pipe and hose should conform to GB/f23510

4.3.3 All metal pipe joints shall comply with Parts 1, 2, 3 or 4 of IS08434:1995.

4.4 Paint circulation system

The paint circulation system is a type of pressure centralized paint system. The system relies on the circulation of paint liquid to solve the precipitation problem occurring during long-distance transportation during medium- and large-scale painting.

For paint liquids that have a tendency to settle at rest, a paint circulation system is required when the paint supply system supplies materials to more than three spray tools at the same time or the daily consumption of paint exceeds 60L.

4.4.1 Recycling of the paint circulation system

The circulating mode of the commonly used paint circulation system is the main circulation, the two-line circulation and the three-line circulation

4.4.1.1 Main circulation

The main circulation is one of the simplest circulation systems. It consists of a set of tubes of the same size and lacquered, lacquered parts joined together to form a loop, and the paint circulates in the tube. In the main circulation system, the branch line of the spray station does not participate in the cycle, so it is also called the "dead end circulation system". Each spray station in the main cycle has a paint regulator that regulates the pressure and flow supplied to the spray gun. The design supervisor should minimize the length of the non-circulating manifold when circulating the paint.

4.4.1.2 Two-line circulation

The two-line system relies on two sets of gradually tapered pipes to balance the flow in the entire pipe. The branch pipes in the two-line system also participate in the cycle, the so-called "cycle to gun system". By adjusting the pressure and flow rate of the paint flowing through each spray station by changing the size of the pipe, the two-line circulation system does not need to use the paint regulator of the gun station to control the paint pressure and flow rate of each spray station, in the whole system. Only one back pressure regulator is used to adjust the pressure of the system, and a pressure regulator or throttle valve is used under the gun to control the pressure and flow of the gun.

4.4.1.3 Three-line circulation

The three-line circulation system consists of a high-pressure circulating paint supply pipe and a low-pressure gradient return pipe. Each spray station in the three-line system contains a paint regulator. The branch pipe in the three-line system participates in the cycle and is also recycled to the gun. system. The spray station paint regulator in the three-line cycle cooperates with the high pressure circulation pipe and the back pressure regulator at the end of the low pressure return pipe to control the branch flow return flow of each spray station. The pressure and flow supplied to the gun in the three-line system is controlled by a sub-pressure regulator or throttle valve installed under the gun.

4.5 Basic requirements for paint recycling systems

4.5.1 Pressure requirements

The design of the paint circulation system should meet the requirements of the process for the pressure of the paint liquid. If there is no special requirement in the process, refer to the requirements of Table 1.

 

All spray positions

>0.2MPa

 

4.52 Basin requirements

The design of the paint circulation system should meet the requirements of the process flow rate of the paint liquid. If there is no special requirement in the process, refer to the requirements of Table 2.

 

Per flow rate

>350ml/min

 

4.5.3 Flow rate requirements

The manufacturer of the paint liquid material shall propose the flow rate requirements, and refer to the requirements of Table 3 if there is no special requirement for the process.

 

Flow rate in the return line during spraying

0.15m/s-0.35m/s

4.5.4 Material requirements

All equipment and materials in the paint recycling system do not allow the use of any materials containing silicon, asbestos and grease. The part that touches the coating should use a solvent-resistant material.

4.6 Composition of the paint circulation system

The paint circulation system includes a central paint supply system, a gun station outlet assembly, piping and control systems.

4.6.1 Central paint supply system

The central paint supply system consists of circulating fluid pump, paint liquid tank and agitator, regulator, filter, back pressure valve and other paint treatment components.

4.6.1.1 Circulating pump

The main circulation pump should be able to meet the flow, pressure and chemical compatibility required by the process. The main circulation pump can use a centrifugal pump, a plunger pump or a diaphragm pump, and the driving method can be air driving, hydraulic oil driving or electric driving. For water-based paints, the circulation pump requires stainless steel of OOCr19Ni9 or higher and all parts that are in contact with the paint must be electrolytically polished and passivated.

4.6.1.2 Paint cans

The paint tank should be made of stainless steel as a whole, and its corrosion resistance is not lower than OCr19Ni9. The paint cans are made of a dish-shaped head and a conical head. The bottom of the tank is inclined. The bottom of the tank should be equipped with an interface to facilitate connection with the pipe. All welds on the tank should be smooth and free of irregularities. All scratches on the inner wall of the tank should be polished.

Agitator should be installed in the paint tank, and the solvent and curing agent tank can be installed without a stirrer.

A flat cover with hinges shall be provided on the paint can. The cover shall have openings for the installation of the stirrer and the level gauge, and the seal between the cover and the can shall be strictly ensured.

For water-based paints, the top of the paint can should be designed in a circular arc shape. There is no spoiler inside the paint can.

Under normal circumstances, the volume of the paint can should not exceed 1000L.

4.6.1.3 Agitator

Pneumatic or electric agitators can be used on the paint cans. Flange type installation should be adopted between the paint cans. The rotation speed, blade size, shape and length of the agitator should match the size of the paint liquid and the paint can. . The speed of the agitator can be adjusted from zero to maximum speed, and the paddles should be designed to prevent vortexing of the material in the tank and to mix the air with the paint.

For water-based paints, the shear force of the blender on the paint must not impair the paint performance.

4.6.1.4 Voltage Regulator

A regulator and a diaphragm pump must be equipped with a voltage regulator. The regulator should be installed at the outlet of the pump to reduce the pulsation of the paint pressure and flow.

4.6 .1.5 filter

A filter is required at the outlet of the pump, and the filter can be a filter cartridge or a filter bag. For a plunger pump, the filter is installed after the regulator. The filter should be easy to repair and replace the filter (bag). There should be a drain valve at the lower end of the filter. The inlet and outlet should have a shut-off valve and a pulsation-proof pressure gauge. The seal inside the filter should be a Teflon covered material. The filter accuracy of the filter or filter bag is determined by the data provided by the paint supplier.

4.6.1.6 Back Pressure Regulator

A back pressure regulator with a pressure gauge is installed on each return line in the paint circulation system. For waterborne coatings, a low shear regulator is required.

4.6.1.7 Hose

The hose should be a non-stick and solvent resistant hose.

4.6.1.8 Level gauge

To monitor the level in the paint tank, a level gauge must be used. The level gauge can use a float, air or electronic level gauge.

4.6.2 Gun station exit assembly

The gun station outlet components include ball valves for paint outlets, paint regulators, paint hoses, and quick-change couplings.

4.6.2.1 Ball valve

All ball valves should use stainless steel of OCr19Ni9 or higher. For water-based paints, it must use OCr19Ni9 stainless steel. The ball valve of 10m m or less is a two-piece ball valve, and the ball valve of 12.5mm or more is a three-piece ball valve. The ball seat and seal inside the ball valve must be made of Teflon. All ball valves must be oil free.

4.6.2.2 Paint Regulator

For the main circulation system and the three-wire circulation system, a paint regulator is installed at the exit of the gun station. The paint regulator adjusts the paint pressure at the exit of the gun station to the desired stability value to meet the needs of spraying or recycling. In a three-wire circulation system using waterborne coatings, a low shear pressure regulator should be used.

4.6.3 Circulation  piping

4.6.3.1 General requirements

The piping should be designed as a constant current system as much as possible. It is not allowed to use the circulation line as a support, guardrail, etc. or to add a load to the pipeline.

4.6.3.2 Steel pipe

For special requirements or special applications, the paint liquid conveying steel pipe should use stainless steel of OCr19Ni9 or higher. Steel pipes shall be made of seamless or internally polished industrial welding tubes, and the pressure rating shall meet the design requirements. The steel pipe shall be passivated and passivated or polished. Before it enters the site, it needs to be degreased and pre-cleaned. During the transportation process, pipe plugs are used to seal the two ends of the pipe to prevent dust from entering. For water-based paints, the lowest grade of steel pipe is OOCr19Ni9.

4.6.3.3 Steel pipe connection

The connection of steel pipes for painting can be in the form of special stainless steel joints, ferrule joints, welding, etc. in the sanitary industry. Thread connections that may cause stepping should be avoided as much as possible, but welding between the spray station and the paint liquid main body is not allowed for disassembly and repair. . The spacing of the joints in the main pipe shall not exceed 12 m. The corrosion resistance of the materials used in the pipe joints shall not be lower than the materials used in the steel pipes. All joints must be degreased prior to installation. The welding of painted steel pipes must use a fully automatic orbital welder. The welding method is non-filled tungsten gas shielded welding. The weld must be wiped and cleaned before welding. The material used for wiping must be guaranteed not to remain on the workpiece after wiping. Inert gas must be used for bead protection on both sides of the weld when welding.

4.6.3.4 Installation and construction of pipelines

The piping should be installed to minimize installation pressure. The distance between the pipes should be guaranteed not to affect the disassembly and repair of the pipe joints.

The pipe support should not damage the pipe. Recommended values for the maximum distance between horizontal pipe supports are shown in Table 4.

Table 4 Pipe support distance

 

D>50

3

 

The main circulation pipe is not allowed to use 900 elbows, and the curved pipe radius should be not less than 6 times the outer diameter of the steel pipe. Measures should be taken to prevent the pipe from being thinned and reduced in diameter when the pipe is bent. The pipe diameter deformation must not exceed 50% of the pipe diameter. Pipes cleaned by a through-pipe cleaner shall not deform more than 0.5 mm in diameter.

When the steel pipe is cut, the verticality of the fracture must be ensured. The cut pipe end must be trimmed to ensure that there is no flash and dimensional change at the fracture. Before installation, the compressed air blowing and solvent wiping should be used to remove the impurities remaining in the pipe. Such as chips and so on. Wipe the material of the pipe to ensure that it does not remain in the pipe.

4.6.3.5 Pipe insulation

When the paint temperature control system is used for paint supply, the pipe needs to be insulated.

Each pipe should be insulated separately and the insulation should be made of flame retardant materials. The thickness should be determined according to the ambient temperature and temperature control accuracy but not less than 12.5mm.

4.6.3.6 Marking

After the installation of the pipeline, at least in the paint booth, on both sides of the spray booth and outside the paint booth, it is easy to observe the location of the system number, the flow direction of the paint liquid and so on. For insulated pipes, the marking should be outside the insulation

4.6.4 Paint liquid temperature control system

The general coating temperature should be maintained at 200C - -300C} The temperature control accuracy should be determined according to the performance of the paint liquid material. Waterborne coatings, high solids coatings and airless spray coatings can reach temperatures up to 500C-600C.

4.7 Cleaning and testing of paint circulation system

After the installation of the paint circulation system, it must be subjected to air purging, airtight test, pressure test and cleaning. After passing the inspection, it can be used.

4.7.1.1 Equipment and piping that are not allowed to be purged shall be isolated from the piping that is allowed to be purged.

4.7.1.2 Prior to purging, the regulating valves, instruments and important valves in the pipeline shall be disassembled or protected.

4.7.1.3 The sequence of purging should be carried out once in accordance with the main pipe and the branch pipe. The dirt that is blown out must not enter the cleaned pipe.

4.7.1.4 Before pipe cleaning, check the tightness of the pipe supports and hangers, and fix them if necessary.

4.7.2 Air purge

4.7.2.1 Air purging should use dry, oil-free compressed air. The pressure of the purge should not exceed the design pressure. The flow rate should not be less than 20n1/so.

4.7.2.2 During the air purging process, when visually exhausting the fumes, the wooden target plate with white cloth or white paint shall be set at the exhaust port, and the target plate in 5nun shall be free of rust, dust, moisture and oil. Other impurities such as drops are acceptable.

4.7.3 Airtight test

The airtight test of the circulation system shall use oil-free compressed air at a pressure of 0.5 MPa. In the airtight test, all joints and welds are inspected with a blowing agent, and no leakage is acceptable.

4.7.4 Pressure test

4.7.4.1 Test media

The pressure test of the circulation system shall use nitrogen as the test medium, and the test pressure shall be 15 times of the design pressure. When the test conditions are not met at the site, the solvent recommended by the paint supply unit may be used as the test medium with the consent of the user.

4.7.4.2 Test method

During the test, the pressure should be gradually increased gradually. When the pressure rises to 50% of the test pressure, if no abnormality or leakage is found, continue to increase step by step according to 10% of the test pressure. Each stage is regulated for 3 minutes until the test pressure. After the voltage regulator IOr nin, the pressure is reduced to the design pressure, and the voltage regulation time should be adjusted according to the leak detection time, but not less than 30 minutes, and the foaming agent is not qualified for leak detection.

4.7.4.3 Cleaning and commissioning

The supply unit of the paint liquid material shall provide the materials, methods and qualification standards for cleaning, and the equipment supplier shall be responsible for the operation of the equipment for cleaning. The results of the cleaning must be approved by the remnant inspection, the oil point test and the supplier of the paint liquid material.

The circulation system must detect the flow and pressure of each spray station before the official use of the injection system (except for the main circulation), and adjust the system parameters according to the measured results. All measurements and inspections should be carried out without spraying.

4.8.1 System Operation

Once the paint circulation system is running, it is necessary to maintain continuous operation, stop the system that has been cycled for more than 2 hours, and must pass at least 1 hour before restarting the use. For the main circulation system, before starting to use it every day, it is necessary to follow the paint liquid in the non-circulation pipeline. The workpiece can only be sprayed after being drained twice as much as the stock.

4.8.2 Daily maintenance and regular inspection

During the use of the paint circulation system, the pressure and flow of the spray station and the system should be checked regularly to ensure the normal operation of the system. When the system parameter changes more than 20% of the fixed value. The entire system needs to be re-commissioned. Items to be inspected daily include: pump operating frequency, back pressure regulator setting, all valve status, and whether the plunger pump's throat seal fluid needs to be replaced or added.

The items to be inspected weekly include: the throat seal of the plunger pump and the pressure at the spray station.

4.8.3 Power source

The power source of the paint circulation system (power supply, pressure Awf2; gas or air compressor, source) needs to be able to provide equipment power to ensure continuous operation of the system during special periods such as holiday and maintenance.

4.9 Automatic color change

4.9.1 Automatic color changing device

The automatic color change device is mostly an integrated block of a plurality of valves. A plurality of color change numbers are formed by a plurality of valves stacked in a block.

4.9.2 Requirements for automatic color changer shortening color change time recommended consideration:

4.9.2.1 Minimize the length of the cleaning pipe when changing colors

Try to change the color of the automatic color changing device in the vicinity of the painting device. The shorter the pipe, the shorter the cleaning time and the less cleaning solvent.

4.9.2.2 Special cleaning valve

A dedicated purge valve reduces jetting resistance. Increasing the flow rate of the cleaning solution and introducing the cleaning waste liquid into the recycling waste liquid container, reducing the pollution of the waste liquid discharge and improving the cleaning quality.

4.9.2.3 Using the sprayer lining regulator

The needle valve of the gun is fully opened by using a sprayer flow regulator. In the color change cleaning, firstly, the predetermined compressed air (0.3MPa-0.4MPa) is added, and then the paint circuit of the sprayer regulator is completely opened to reduce the resistance during cleaning.

4.9.2.4 Using the Pipe Cleaner

When cleaning, it is difficult to clean the pipeline only by thinner. Generally, the diluent valve and the compressed air valve are alternately switched to improve the cleaning efficiency. The hose cleaner forms a mixed state of diluent and air to clean the hose, which also reduces the amount of diluent used.

4.9.2.5 Use of PTFE pipes

The inner surface of the paint pipe should be made of materials with a small coefficient of friction, especially from the automatic color change device to the pipe of the sprayer, using PTFE as the material.

4.9.2.6 Problems to be noticed in the paint interface

The coating interface should adopt a structure with small step height difference and less dead angle.

4.9.2.7 Using a squeeze air valve

In order not to waste paint, compressed air is used to extrude the residual paint. The paint loss during color change can be minimized and the cleaning time can be shortened.

4.9.3 Common Color Change System

Commonly used color change systems have multiple fixed color full configuration methods, two-color cycle configuration method, fixed color and automatic color change device combination configuration method.

4.9.3.1 Multiple fixed color full configuration method

When the number of color change is small or the color change is large and the color change is frequent, the automatic color change device is determined according to the number of color changes required.

4.9.3.2 Two-color cycle configuration method

The two-color configuration method uses two loop-type automatic color changing devices, which is an effective method for coloring a large number of colors, but a large number of color-changing times per day. Switching of the A-valve-B valve is possible. Then use the replacement valve to change color for use.

4.9.3.3 Fixed color and automatic color change device combination configuration method.

The fixed 1 or 2 colors are fixed color automatic color changer, and the remaining colors are configured using the two-color loop configuration.

4.9.4 Maintenance of color change system

The paint should be thoroughly filtered to reduce foreign matter blockage between the moving valve and the thin pole.

Paint leakage occurs after the pin seal and filler wear, and should be replaced as soon as possible

5 Safety, environment and sanitation

5.1 The paint supply system should be installed in a clean, dry, and airy place. The environment a degree fi`v is kept at 100C-350C, and the relative humidity is not more than 75%.

5.2 Strict fire, explosion and anti-virus measures should be taken to ensure safety.

5.3 The safety of the installation site of the paint supply system shall comply with the requirements of GB 6514.

Painting and lacquering The sanitation of the installation site shall comply with the requirements of GB7 691.

5.4 Accidental handling:

In the event of fire and other accidents, stop the paint pump immediately and stop pumping the paint. In the paint booth, the spray booth should be equipped with a fire alarm and a interlocking device that automatically stops the paint pump.

6. Inspection items and methods

Inspection according to the items agreed in the supply contract

6.1 Inspection of main design parameters

Check the system's main pressure, main flow, tube flow rate, and main configuration.

6.2 Inspection of the structure and key parts of the system

Inspection of system layout, pipe connections, pipe fixing, and installation of major components.

6.3 System leak test

Full pressure leak test, check for leakage and vibration.

6.4 System commissioning

Test the system for full pressure. The inspection system shall be used for the paint condition and the full load inspection of the spray gun according to the contract.

6.5 other

6.5.1 Check for potential safety hazards and precautions.

6.5.2 Check the variety and quantity of consumables.