Wet Versus Dry Pumps

Vacuum pumps are critical for use in industrial, laboratory, and research applications. When making your decision, consider the flow rate, compression, elastic ability, pressure capacity, cost, and maintenance. Wet pumps and dry pumps both have particular features unique to their design. Learn more about them and you’ll make the right choice that is perfect for your needs.

The Main Difference Between Wet Pumps and Dry Pumps

Water-based wet pumps use water to seal or lubricate. Oil-based pumps use oil. Dry pumps use PTFE dry polymer seals instead of water or oil. A dry vacuum pump may also have a diaphragm to keep the swept gas away from the mechanism that pumps.

Types of Wet Pumps

Rotary Vane – Oil-sealed

The structure of the rotary vane pump is sturdy and it holds oil long. The oil seals the pump. The oil cools the vanes as well.

Industry best uses include:

• Packaging
• Paper manufacturing
• Printing
• Woodworking

Liquid Ring

The simple wet pump design features two moving parts: the shaft and impeller. The liquid ring pump was created for dewatering and filtration processes.

Industry best uses include:

• Vapor loads
• Distillation liquid carryover (where a high tolerance is required)
• Drying processes
• Evaporation processes

Benefits of Wet Pumps

• Economically priced
• Costs less to rebuild
• Resists corrosion
• Reaches high pumping speeds
• Has a higher tolerance for moisture and contamination
• Average longer lifespan in-between rebuilds if preventive maintenance steps are taken
• Not as noisy as some dry pumps

What Else You Need to Know About Wet Pumps

There is a higher contamination risk in a wet pump. This is because the sealing or lubrication fluid can contaminate the pumped gas. In addition, liquid waste must be properly disposed of.

If you invest in a wet pump and later decide you want to convert it into a dry pump, it will be challenging. There is a risk of contamination when going from wet to dry. The chamber and the piping must be cleaned very well or better yet, replaced. Otherwise, the gas will be contaminated.

Furthermore, wet pumps require oil changes and this tends to be messy. Another important point to make is that the pump may receive oil into its inlet side when it reaches its vaporization point.

Types of Dry Pumps

Claw

The claw pump design offers a high flow rate with the ability to endure tough industrial settings. Manufacturing plants can increase efficiency by operating multiple claw pumps at different assembly line speeds.

Industry best uses include:

• Molding machinery
• Packaging lines
• Pneumatic conveyors

Rotary Vane – Oil-less

The dry rotary vane pump was designed for continuous running at maximum vacuum and pressure. This rotary vane at High Vac Depot is durable, runs quietly, and requires little maintenance.

Best uses include:

• Packaging
• Woodworking
• Pneumatic conveyors
• Rotary Screw

The rotary screw pump is typically quieter than oil-sealed wet pumps. It has a variable speed drive for efficiency. The pump adapts well in rigorous environments too. The rotary screw fits large industrial settings where a maximum throughput capacity is required.

Industry best uses include:

• Food packaging
• Glass manufacturing
• Plastics manufacturing

Benefits of Dry Pumps

• Low-maintenance because no oil changes are required
• No contamination risk from oil seals or water seals
• Long-term savings due to low maintenance
• No oil or water waste is produced from the dry pump
• Minimal downtime because of less maintenance

What Else You Need to Know About Dry Pumps

• Costs more to purchase
• Rebuilding is costly
• Moisture sensitive so contamination could occur if moisture is introduced into the system
• Possibility of major damage to hard parts such as bearings

Flow Rate Differences

Since dry pumps are pneumatic, they tend to operate more efficiently than a hydraulic system that uses liquid. However, it depends on the application. When fast volume processing counts, pneumatic may be the best choice. If you are processing very large loads and there is no room for error, hydraulic pumps (wet pumps) may be more suitable.

Wet and Dry Pump Compression and Elastic Abilities

Concerning compression, dry pumps can be a better choice in certain situations. For example, you may have a process in which a weighty load needs to be brought safely to the ground. A dry pump uses pneumatics so it will perform better at laying down the load than a hydraulic wet pump. You will sacrifice total accuracy in timing as it may be a bit delayed in its movement though.

Air bounces back in a dry pump system making dry pumps more able to adjust to load variations. This elastic ability is an advantage over a wet pump.

Just as little as two decades ago, wet pumps were extremely popular. Advanced technology has pushed dry pumps to the forefront. Today, many industries are choosing to forgo the messy oil changes that are the hallmark of wet pumps. Instead, more companies prefer to use dry pumps to lower maintenance and reduce oil contamination risks.

High Vac Depot has a large selection of wet and dry pumps at different price points. The key to making the right decision is to take an in-depth look at your application process. Our specialists are here to assist you in choosing the right wet or dry vacuum pump to meet your needs. Call us at 1-800-289-6945 or contact us online today!