Many customers are becoming energy conscious and are reviewing existing production equipment to look for ways to save energy. One major item of consideration is the cost of compressed air. For fluid transfer requirements, many customers will use an Air Operated Diaphragm pump.
For a typical 2" AOD pump to transfer 50 GPM of light weight fluid with a discharge pressure requirement of between 40 to 50 psi and an inlet air pressure of 70 psi, it will require approximately 50 cfm of air (this converts to approximately 12 BHP). If the fluid is viscous and has a higher discharge pressure requirement, the inlet air pressure for the AOD pump can increase to 100+ psi and will require 25 percent+ more flow.
This was evidenced by my customer, RUSTOLEUM in Decatur GA who manufactures coatings. They were using a 3” AOD pump to transfer a viscous 1500 cps, high particulate metallic coating that is very abrasive. The AOD pump had an inlet air pressure of 120 psi and a discharge pressure of approximately 30 psi which resulted in a discharge flow of 40 GPM. The required cfm of air was approximately 60 cfm (15 BHP).
Due to the pulsation seen on piping and valves, they were also using a BLACOH 2” pulsation dampener. Because of the abrasive nature of fluid, the AOD pump required service with new wetted parts every 3 to 4 weeks which was totaling around $500 per repair.
The customer wanted to expand production with a required flow of 60 GPM and would need two 2” AOD pumps to accomplish this, which would be around 50 to 60 cfm for 30 GPM @ 120 psi (converts to 15BHP).
In an effort to reduce both the maintenance costs as well as the energy costs, a VIKING LS4124A 3” internal gear, positive displacement pump was supplied. We c-face mounted the pump to a speed reducer and drove the package with a Premium Efficiency 7.5hp 1750 rpm motor. The pump is typically supplied with carbon graphite bushings but we replaced those with hardened iron bushings; and we also converted the pump from a mechanical seal to packing, expecting a short seal life due to the abrasive nature of the fluid.
The Viking LS4124A pump is supplying a transfer rate of 65 GPM and is seeing reduced parts replacement. The transfer rate was reduced by almost 30% using the Viking PD pump compared with the AOD pumps. And the power requirement was reduced by 50 percent.
Based on this improved performance, Rustoleum has now converted their West Virginia plant from AOD pumps to VIKING positive displacement pumps for this same sand based, high viscous fluid.
RUSTOLEUM still uses various AOD pumps for their light weight water based fluids.