Pump Primer

Pump applications can be far reaching — from the general-construction dewatering job, to flood control, to unique applications in the fishing and recreational industries — meaning big business for rental centers. These varying applications suggest that rental customers will have different levels of pump knowledge regarding the type of pump needed for their particular job. Rental centers and their customers can choose from a wide range of pumps, and selecting the correct pump for the application is important.

The most common pumps available for rental are trash, dewatering, diaphragm and submersible pumps. Each of these pump styles is designed for different applications. Centrifugal trash and dewatering pumps are very versatile and are among the simplest and most efficient.

Dewatering

Dewatering pumps are relatively inexpensive, but generally do not contain high-quality components. The water being pumped must be relatively clean, containing solids up to ¼ inch in diameter and less than 10 percent by weight. Benefits of dewatering pumps include high volume flow capabilities and a lightweight, compact design. These pumps are best suited to pump unwanted water from flooded basements, utility vaults, swimming pools, lakes and barge holds. Dewatering pumps can also supply water to rural fire trucks, water trucks and small irrigation projects.

Trash

Trash pumps contain many high-quality components and are well worth the additional cost. This type of pump is often the preferred choice in the construction industry. These pumps can handle clean, muddy, mucky or sandy water with solids up to 2 inches in diameter (depending on pump size) and between 10 to 25 percent by weight. Applications include pumping unwanted water from excavations, flooded basements, manholes, utility vaults, mining work, swimming pools, lakes and barge holds. Trash pumps are popular in the rental industry because of their reliability and versatility.

Submersible

Submersible pumps offer contractors versatility on the jobsite. These pumps are primarily for water containing solids up to ¼ inch in diameter and less than 10 percent by weight. They are relatively inexpensive, can run unattended, and are lightweight and quiet. Pumping unwanted water from well casings, tunnels, shafts, flooded basements, manholes, vaults, swimming pools and farm field drainage collection systems are some applications appropriate for submersible pumps. They can also supply water to fountains, waterfalls and small irrigation projects. Submersible pumps are directly connected to an electric motor and are lowered directly into the liquid to be pumped.

Diaphragm

Diaphragm pumps are effective in muddy applications and are often used where the content of solids is high and/or a condition of seepage exists. Because of this muddy application, diaphragm pumps are commonly referred to as mud hogs, mud suckers or simply mud pumps. While diaphragm pumps do not pump high volumes for their weight, they are useful because of their versatility. Diaphragm pumps have the capability of pumping water with greater than 25 percent solids by weight. Diaphragm pumps do not require a steady flow of water and can handle large amounts of solids.

Basic operating tips

High-quality pumps require preventive maintenance and, most of all, proper operation to maintain levels of high performance. The following basic guidelines will ensure a pump operator many hours of successful and trouble-free operation:

• Position the pump as close to the source as possible, using the shortest suction hose possible. The shorter the distance a pump has to move liquid, the higher the volume the pump will deliver. Long hoses produce more friction and ultimately less volume.
• Check the suction hose for leaks and secure all fittings. Most pump failures are caused by faulty suction hoses or connections. Even a tiny pinhole on the suction side may cause the pump not to prime.
• Check that the discharge hose is not kinked. If this hose is pinched or clogged, air cannot escape and the pump will not prime.
• Always use reinforced hoses on the suction side to avoid collapse.
• Always run the pump at the manufacturer's specified rpm. Running at lower than recommended rpm can decrease pressure head and flow rate.
• Make sure the suction hose has a gasket.
• Use the proper strainer to avoid clogging and damage.
• Make sure flapper valves are operational.
• Prime the pump (fill the pump housing with water) before use. Make sure the check-valve is operational and check the pump vacuum at its suction inlet.

Trash, dewatering, submersible and diaphragm pumps are all an important part of any rental fleet. Understanding the various applications each type is designed for will help rental center operators recommend to customers the right pump for their specific job.

Mark Conrardy is sales engineering manager for Menomonee Falls, Wis.-based Wacker Corp.

Trash and dewatering pumpsSubmersible pumpsDiaphragm pumpsCapabilities • 25-foot suction lift at sea level
• High discharge heads
• Lightweight and portable
• Small investment for large capacity
• Few parts, easy to maintain • No suction hose required
• High discharge heads
• Small investment for large capacity
• Few parts, low repair and service costs
• Instant priming
• Runs dry for short time
• Does not need constant attention
• No lifts to calculate • 25-foot suction lift at sea level
• Full capacity on each stroke
• Handles low seepage
• Keeps pumping in shallow water
• Pumps mud and large amounts of solids
• Easy service valves and diaphragm Limitations • High water content to move solids
• Not for mud and thick slurries
• Dewatering pumps: 10 percent solids or less
• Trash pumps: 10 to 25 percent solids • Must be pulled out for inspection
• Electric power source required
• 10 percent solids or less • Low discharge head and pressure
• Small capacity for investment versus centrifugal models
• 25 percent solids and above Applications • Clear water
• Water with algae
• Water with suspended clay
• Silt water
• Abrasive water
• Fast seepage ditch water • Water with algae
• Water with suspended clay
• Abrasive water
• Slow seepage ditch water • Water with algae
• Water with suspended clay
• Mud water
• Silt water
• Abrasive water
• Water with high solid content
• Slow seepage ditch water
• Septic tank