Fluid dispensing has seen a lot of technological advancement with many different dispensing techniques being introduced along with many sophisticated equipment. Choosing a dispensing valve for your application can be a daunting task especially if you don’t have much information about the kind of options available.

Let’s go through some of these different dispensing valve types before diving into the tips of how to choose the best dispensing valve for your application.

Types of dispensing valves

The kinds of dispensing valves that you can encounter from very simple, manual ones to much sophisticated and advanced valves are discussed below.

Manual syringe system

This is the simplest form of manual dispensing. This dispensing is done by an operator holding a syringe of fluid that is connected to a standard desktop dispenser. The operator will dispensed onto area of interest by hand movement. Dispensing time and pressure for the syringe can be set on the desktop dispenser. This method is low cost and works for applications that does not requires any precision.

Diaphragm valve

This valve comprises a diaphragm that allows or restricts the fluid to flow through. When the fluid is to be dispensed, the air pressure forces the diaphragm to pull back, creating an opening for the fluid to flow through. When the air pressure stops, the diaphragm pushes back to its position to restrict the flow. Since the diaphragm is made from an ultra high molecular weight polyethylene (UHMWPE) material that prevents moisture from coming in contact with the fluid, this valve is a good choice to be used for dispensing moisture-sensitive liquids.

Pinch tube valve

The pinch tube valve is one of the simplest types of dispensing valves that comprise a disposable plastic tube. Fluid flow through this plastic tubing. To stop, this tube is automatically pinched. This valve can be used on a wide range of viscosities. Since the plastic tube that comes in contact with the fluid can be disposed of, this valve can be used with quick curing adhesives or other types of fluids that may cure inside the valve.

Needle valve

Needle valve can be used in applications that require micro-dot sized deposits as small as 0.0005 cc. This single or double-acting needle valve works with a pneumatic trigger that opens or closes when the air pressure signal changes. The air pressure causes the needle to lift from the position to allow the fluid to flow whereas when the pressure signal ends, the needle moves back to its closed position. This valve can be used for materials with a wide range of viscosity such as inks, oils, primers, solvents, and UV adhesives. Quick-curing adhesives and moisture-sensitive fluids should be used with this valve without modifications.

Spool valve

Spool valve is a heavy-duty valve that can be used to dispense high-viscosity fluid in large volumes. The valve comprises air-actuated pistons that move to open or restrict the fluid’s flow path. It works in an opposite way to that of a needle valve as the air pressure pushes the piston down to open the fluid path whereas when the air pressure stops, the piston lifts up to close the fluid path. When it lifts, it creates a vacuum that prevents the liquid from dripping after dispensing is stopped. This valve is usually used to dispense grease, sealants, and for filling cartridges.

Progressive Cavity Pump

A progressive cavity pump is used to dispense liquids in those applications that require immaculate precision and accuracy. The pump comprises a cavity stator that holds a rotor that rotates in it. The rotor and cavity are helix shaped that create air-tight cavities. When the rotor rotates, the fluid is pushed through the pump. Thus, with each rotation, you get the exact, accurate amount of fluid. These type of pumps do not get affected by the pressure or viscosity of the liquid. They are used for dispensing various types of materials (from low viscosity to very pasty) and can be used for encapsulation, gasketing and potting applications.

Auger valve

Auger valves are widely used for high-accuracy dispensing of solder, silver paste and high viscosity materials. This valve can be used for dotting and or for a gasket application with good consistency. It dispenses through a rotating lead screw that is usually driven by a servo motor. However this valve does not work well for low viscosity fluid. We have a few auger valves for selection, such as AV100, AV200 and AV300.

Jetting valve

A jetting valve is primary used is to dispense liquid at a much faster pace as it does not need to be raised or lowered when moving from one dispensing location to the next location. Its performance is further enhanced when jetting “on the fly”. Some applications that use jetting valves are underfill, substrate with undulating surfaces, hard to reach areas, solder and silver paste dispensing.

Ball valves

Ball valves comprise a simple mechanism that is used to open or shut off fluid flow. They are easy to use and are available in a variety of materials which makes them a versatile choice to be used in many different applications. Ball valves for dispensing are usually made of stainless steel. This valve is good for medium to high-viscosity materials and for dispensing of lines.

Tips for choosing the right dispensing valve

Once you have a clear understanding of the various types of dispensing valves available, we go through some tips that you should keep in mind while selecting a particular one for your applications.

Consider the right valve type

First and foremost, identify the type of dispensing you want for your application. As discussed above, each type of valve work differently and is designed to be good for certain specific applications. Some are able to dispense large volumes at one time whereas others can dispense very small beads of continuous fluid. Similarly, each valve has a different requirement of the kind of fluid it can dispense, some only work with high-viscosity fluid whereas others work with low-viscosity ones.

Types of Fluid to be dispensed

It is important to know and understand the fluid that one is going to dispense. This is necessary in order to match it to the correct type of valve or its configuration. For example, dispensing of CA or anaerobic materials will require plastic wet bodies. Abrasive fluid will require a valve that can resist and withstand the potential damage by abrasive particles in the fluid. Corrosive fluid may work well with a plastic valve rather than a metal one.

Specific dispensing requirements

Every application will have its specific requirements. Some need very specific dot sizes, some require constant line width and there are some with UPH requirements. It is important to look at such specific requirements and match it to the capabilities of the valve.

Keep maintenance in mind

Finally, maintenance is another important factor that must be considered while choosing a dispensing valve. Whatever valve you choose for your application system will require regular maintenance to ensure its efficiency and reliability. If a valve requires less maintenance over time as compared to another that requires very frequent maintenance, then the former should definitely be preferred over the latter. Moreover, keep the maintenance aspect in mind while considering the costs of valves. One valve may be cheaper upfront but may require frequent maintenance which will cost you more in the long run. So a relatively expensive valve may be preferred which will not require that frequent maintenance.

TechnoDigm has been providing dispensing and UV curing solutions to the industry for over two decades now. We are a one-stop technology partner that can fit any kind of production environment and provide you with excellence and engineering by utilizing technological innovations. Contact us today to find more information about dispensing valves and much more.