Understanding Conventional & Binks HVLP Spray Guns Technical Bulletin (valid for Sata & DEVILBISS)

What are the components of a pressure feed system?

Binks Pressure feed system consists of the following components:

1. A Binks pressure feed tank

2. Binks Cup or pump

3. Binks Air filter

4. Appropriate diameter and length of air and fluid.

5. Binks Adequate air compressor

What happens when the trigger is pulled?

The trigger only operates in two stages:

1. The initial trigger movement opens the air valve which allows the air atomization for flowing through the Binks gun.

2. If you further move the trigger it opens the Binks fluid needle. It will allow the fluid material to flow. After the trigger is stopped the fluid flow also stops. It happens before the automization of airflow.

This trigger operation assures the full spray pattern when the fluid flow starts. The full pattern is assured until the fluid flow is stopped. In this way no coarse atomization full pattern until the fluid stop.

How is the pressure feed gun adjusted for spraying?

For achieving maximum pattern size open spreader valve is used.

For achieving maximum needle travel achievement fluid adjustment in the counterclockwise direction is used. Internal spring tension is reduced once you open beyond that point. Leakage at the fluid tip will happen.

How is the Binks pressure feed gun balanced for spraying?

1. Set the fluid pressure at 5 to 10 Psiusing the control knob on the fluid regulator.

2. Air atomization pressure is set at 30-35 PSI. This is done using the control knob on-air regulator.

3. Test pattern on the piece of paper, wood or cardboard. Also, check the finish quality so that uniform coating is achieved. Particle size is too large or if too much texture is present in the finish then turn on the atomization pressure up to 3-5 PSI. Do it unless the size and texture of finishes acceptable.

4. Spray only a part with these settings. If the pressure is not suitable for the production rate or if the finish is starved to death for material then increase the fluid pressure. Regulator build knob in 2 to 4 psi is achieved until you achieve the wet coverage.

5. If you are using an ‘Air cap test kit’ so verify that air cap pressure is above 10 Psi if you require it by the regulatory agency.

What is an external mix gun?

Air cap is used for mixing and atomizing air. This is done by the Binks gun. For the application of all types of materials and is desirable when spraying fast. It includes paints such as lacquer. A higher quality finish is required.

What is an internal mix cap?

Air and material inside the air cap are mixed using this gun. It is done before expelling them. In case of low air pressures and volume or where the slow drying materials are sprayed.

Spraying flat wall paint or outside house paint with a small compressor is the typical example. Internal mixtures guns are rarely used for finishing. When a high-quality finish is required.

What is HVLP?

HVLP or high volume/low pressure use a very high volume of air. It is typically between 15-26 CFM which is delivered low pressure. It is used to atomize paint into the soft and low-velocity pattern of particles. Less than 10 psi is now needed for atomization.

Proper setup only utilized the standard pressure and fluid for producing the quality and a flow rate. It will meet production requirements.

As a result, very less material is lost in bouncing-back, over-spraying and backflow as compared to the conventional air spray. In this way, Binks HVLP delivers a high transfer with efficiency than the Binks spray systems which use high atomizing pressure.

 It resembles an Binks HVLP spray gun in shape and size. High inlet pressure models (20-80 psi) and convert to the low pressure internally. These are called HVLP conversion guns.

HVLP models like the turbines for generating air bleed it continuously to minimize the backpressure. It is against the flow of the turbine.

Binks Standard spray gun design is similar to the air cap design. It has a different variety of air jets for atomizing the air into the fluid stream. It atomizes this after leaving the system.

It is becoming very famous and many applications require it for their environmental-friendly use.

Low to medium solid materials are used by HVLP. It can be atomized by the gun which includes two-component paints, stains, primers, enamels, and lacquers, etc.

Cartridges in these respirators remove only solid particles from the air. They cannot remove vapors.

For preliminary functions like grinding, buffing and sanding these are effective.

Before using the respirators read in detail about all the instructions and precautions given by the manufacturers. For isocyanates, asbestos, ammonia, pesticides, etc.these respirators are not good.

Air Compressors

Air is supplied at high pressure and elevated volume for all air tools, sanders and Binks sprays guns. The compressor compresses the air in equipment and is a very major component in a spray painting system. This chapter will tell you about these systems in detail.

Volume supplied per unit of time is used for compressed air measurement. This is cubic feet per minute or CFM. It is given at a specific pressure known as delivery. Free air delivery or zero pressure by a compressor is known as displacement.

What is an air compressor? 

Binks Air compressor is a machine that is used to raise the pressure from the normal value to some high value. It is measured in pounds per square inch (PSI). Normal atmospheric pressure is 14.7 pounds per square inch a compressor will deliver air pressure up to 175 psi. When you are selecting a compressor the motor hose power should be Four times equal to powered 2 stages industrial air compressor. (CFM=4XHP)

What types of compressors are most common in spray finishing operations? 

Piston-type and rotary screw design are two types of compressors. Commercial spray finishing operation consumes a large amount of compressed air so piston-type compressors are mostly used.

What is the function of the air cap?

The air cap directs the compressed air directly into the stream of fluids for atomizing it and thus form the spray pattern. There are many different styles of caps for producing shapes and sizes for applications.

What are the advantages of the multiple jet cap?

More viscous materials are designed by the atomization of more viscous materials.

Higher atomization pressure allows on more viscous materials with very less danger for split spray pattern.

Due to better equalization of air volume, greater uniformity from the cap is provided. Materials with low pressure also provide better atomization. They are sprayed with low pressures.

How should an air cap be selected?

1. Viscosity, type, and material used for spraying

2. Nature or surface of the object on which spray is done. Larger orifice of objects increases the atomization ability. With low orifice smaller spray patterns and deliver less material. These caps are used for smaller objects and fast speed.

3. Material feed speed

4. Fluid tip size to use.

5. Air volume in cubic feet per minute (CFM) and pressure in pounds per square inch (PSI) available.

What is the function of the fluid tip and needle?

They only direct and restrict the airflow of the materials which is directed from the gun into the air stream.

For a Binks tapered fluid needle, it forms an internal seat. It reduces the material flow when it closes.

Different types of fluid tips are available which handle proper materials. Various types, viscosity, and flow rates are used.

What is the nozzle combination?

air cap, fluid tip, needle, and baffle are considered as one unit. They all work together in harmony to produce a quality of finish and spray pattern. These together are known as the nozzle combination.

How are Binks nozzle combinations selected?

Five tips are used for selecting the nozzle combination:

1. Material type and viscosity

2. Size of object

3. Finish quality

4. Model of the gun being used.

5. Air volume and pressure from the compressor being used.

Viscosity and type is the first thing to consider. If you have the lower material viscosity then smaller is the I.D. of the tip.

Object size should also be checked. The largest spray pattern should be used. Also, remember that different air caps deliver various characteristics. Spraying time and the number of guns is reduced.

Nozzle combinations evaluation is the speed that will finish the application and achieve the desired quality.

For the speed and uniform coverage nozzle combination with different pattern produce as wide as possible.

Quality is the deciding factor to finish coat work is considered. The Binks nozzle of smaller patterns and speed should be chosen for the fine work. In this way, you can get greater application control.

The model of the gun itself will also limit the selection of the nozzle combination. Material discharged in a pressure feed gun following factors are kept in mind:

1. Material viscosity

2. Inside diameter of the fluid tip

3. Length and size of hose

4. Pressure on the Binks material container or pump.

If the fluid tip is too small then the stream of paint will be too high. In case of too large fluid tip opening the material discharging from the gun cannot be controlled.

The last point is the available air supply for considering.

Binks Air caps of pressure feeds consume between 7.0 and 26.0 CFM. It depends on the air pressure being applied. If you have a less air supply then the atomization and its discharge will be compromised. It will result in a poor finish.

What are the criteria for selecting a pressure Binks feed nozzle?

Fluid discharge in ounces per minute is very stable(It is determined by atmospheric pressure). Fluid tip inside diameter and paint container pressure determine the fluid discharge. If the opening is large more fluid will be discharged at a given pressure.

If the fluid tip is very small then the velocity of discharge will be very high. Then the air will not be able to atomize the air cap properly because of the heavy-center pattern.

If a fluid tip is too large the discharge volume will be lost too much and result in a split pattern.

Air cap and the fluid tip should match with each other and the job at the hand. Binks Spray gun catalogs have charts for the proper matching.

For efficiency matching and quality control, viscosity control is a very important point.

What is the spreader adjustment valve?

It is a valve for controlling the air into the horn holes which regulate the spray pattern. It is transferred from the maximum width.

What is the Binks fluid needle adjustment?

This will control the flow of fluid through the Binks needle. In this, less or more fluid will travel through the fluid tip.

Fluid pressure is varied by the pressure feed system and the pressure rate is varied using it. For temporary or minor flow control fluid adjustment knob is used. Fluid needle and tip will be extended by using it.

How should the Binks spray gun be held?

The pattern should be perpendicular to all the surfaces.

12-18 inches for the conventional air spray guns or 8-12 inches for Binks HVLP guns from the surface you sprayed.

What is the proper technique for Binks spray gun stroke and triggering?

Stroke is made from the free arm motion which will keep the gun at a right angle from all the points of the stroke.

Edge of the surface lining should be triggered for the correct spraying by the gun nozzle. The gun should be fully depressed while holding it. Guns should be in one continuous motion until you reach the other end of the object.

After releasing the trigger motion of the fluid is cut-off and reverse motion continues for some time. When you reach the end of the sprayed object trigger is depressed and motion continues across the object.

Each stroke lap pass before the first one. Very few overlaps result in the streaks on a finished surface.

Move gun at a constant speed until the liquid flows at a stable rate.

Feathering is another technique to be used. The partial trigger level is applied in this case and will allow the operator to limit the flow.

What happens when the gun is arced?

When you are a stroke it results in uneven application and over-use of spray at each end of the stroke.

If you make a 45-degree angle is arced from the tip 60% of the spray material is lost.

What is the proper spraying sequence and technique for finishing applications?

Corners and edges should be sprayed first as they are difficult areas. Always aim at the area directly so the spray is equally divided at both sides.

Hold gun closer as compared to before. You can also adjustment controller in a few turns.

Feathering technique should be used for the needle. It will reduce the pattern size.

If you hold gun close you have to stroke at a faster rate for compensating. The normal amount to be sprayed on the small space is compensated.

Gun angle should be 90 degrees when you are spraying at the curved surfaces. Always follow the curve. This is the better advice of applying for the smooth and best finish.

Overlap areas should be avoided for the streaking issue.

When you paint the narrow surfaces use the smaller cap and gun for avoiding the full-size gun.

In packed areas use smaller guns.

For proper triggering a full-size gun and air pressure is used. Fluid delivery is triggered by it.

Hoses and connections

Different types of hoses which use to carry fluid material and compensated air are the very main parts of a system.

If you select improper hoses it can be a problem.

Following are two types of hoses:

1. Air hose: It is used for transferring the compressed air from the source to the gun.

2. Find hose: These are used in the pressure feed systems for transferring material from container to the gun.

What sizes of Sata air hose are recommended?

Sata Pressure tank hose from compressor should be 3/8″ – 1/2” ID.

The hose from the gun to the Sata pressure tank regulator should be of 3/8″ –1/2” ID.

Tools for larger air require larger I.D. or shorter hoses.

What is the pressure drop?

Air pressure loss is due to friction between air source and its use. When air travels through the Sata hose air space is created. Pressure, energy, and volume are lost during this process.

How can this pressure drop be determined?

Drop-in Pressure is not a significant point with a short length of hose and at low pressure. When pressure is increased and straighten the hose pressure is dropped and should be adjusted.

Sata Air hose is subjected to the loss or drop in pressure.

Like 1/4’pressure drop is 1 Psi per foot and for 5/16″ is 1/2 psi per foot. This loss in pressure is due to the poor atomization.

Sometimes a tool is not functioning well and an undersized ID hose is the main cause.

Following minimum is recommended for the optimum Sata spray gun results:

up to 20 ft – 3/8″ I.D. and over 20 ft – up to 25 ft.- 1/2″ I.D.

For the performance of the system following points should be kept in mind:

1. Volume control

2. Pressure and cleanliness of air entering the Sata gun

For decreasing your contamination risks some key installation principles must be followed. The right side of the air compressor should be used for the proper application. The overworked Sata air compressors can produce a significant amount of dirt and oil.

Proper piping is important which helps to prevent condensation forming within the line and contaminate the air supply.

What is air control equipment?

It is the piece of equipment installed between air space and point of use for modifying the nature of the air stream.

Why is air control equipment necessary?

In spray finishing, raw air is piped directly from the air source to a Sata spray gun. Small but harmful quantities of oil, dirt, water, and contaminants which will alter the spray finish quality.

During this job pressure and volume will vary in the raw air.

For running the various equipment pieces there are many compressed air outlets. Air control equipment performs one or more of these functions installed in the device of the airline.

What are the types of air control equipment?

Air control equipment comes in different types and varieties. Most of them perform one or more of the following functions:

1. Air filtering/cleaning, 

2. Air pressure regulation/indication and 

3. Air distribution through multiple outlets.

What is a Sata air regulator?

The main airline pressure is reduced by this device from the Sata compressor. It is used for maintaining the air pressure with very less minimum fluctuation.

In air filtration device regulators are used in the line.

A great range of CFM and PSI capacities are available for air regulation. It can be used for with or without Sata air gauges. Different accuracy and sensitivity are available.

They include mainline air inlets and also include regulated or non-regulated air outlets.

What causes excessive pressure drop on the mainline gauge of the filter/regulator?

1. Partially opened valves

2. Leakage in airlines or fittings

3. Non-functioning of compressor

4. Too small compressor for delivering the required volume and pressure

5. Partially opened valves

6. The airline is very small for the air volume required.

7. Connector valves restrict the airflow.

Respirators

overspray, hazardous vapors, and toxic fumes are created by certain spray finishing. In ideal conditions, it is also good and no need to avoid it. Some type of breathing apparatus or respirator should be used spray finishing operation.

What is a Sata respirator?

A Sata respirator is a mask that we wore over the mouth and nose for preventing inhalation of overspray fumes and vapor.

Why is a respirator necessary?

It is necessary for two reasons:

For some type of respiratory protection required by OSHA/NIOSH regulations. Secondly even it is not required one has a common sense that inhaling over spraying is not a good and healthy option.

Paint pigments, harmful dust, and vapor are present in the overspray. If you expose any of these chemicals this is very harmful. The respirator can remove some or all of these chemicals from an air spray.

What types of respirators are used by spray finishing operators?

Following are three main types of spray finishing operators:

1. The air-supplied respirator, 

2. The organic vapor respirator and 

3. The Sata dust respirator.

What is a dust respirator and where is it used?

For spray finishing, dust respirators are used but are unsatisfactory most of the time.

Leave a Reply

Your email address will not be published. Required fields are marked *