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Guide To Properly Starting Up Your Hydraulic Diaphragm Metering Pump

by PSG | Feb 20, 2023

Since 1961, Neptune® has provided pumping solutions for a variety of industries, including agriculture, oil and gas, chemical processing, and water and wastewater treatment. Among these solutions are precise and accurate hydraulic metering pumps designed to handle large and small capacities in a range of viscosities and pressures. But like all pumping technology, Neptune hydraulic metering pumps require a proper start-up process for optimal performance. 

The following step-by-step guide will help ensure the proper start-up of 500, 560, 600 and 6000 Series Neptune hydraulic metering pumps.

Step 1 - Fill The Pump With Oil
Locate the gearbox that sits in the back of the pump. Remove the cap and fill the gearbox with oil up to a quarter to a half inch below the bottom fill threaded hole or right above the piston. Note: If there isn’t enough oil in the pump, it will not function properly. See the manual (IOM) for the recommended amount of oil to add for each pump model. Once the right amount of oil is in the gearbox, place the cap back.

Step 2 - Adjust the Manual Stroke Setting
Rotate the manual stroke setting counterclockwise to reduce the flow and amount of oil that is bypassed inside the pump. During the manual stroke adjustment, while the oil travels from the gearbox over to the piston and into the diaphragm area, air will accumulate inside the oil side of the pump. For proper pump operation, it’s essential to purge this air.

Step 3 - Purge The Air From the Oil Side of the Pump
Find the air purge plug that is located right behind the diaphragm. Use an Allen wrench and loosen the plug. The air inside the diaphragm area will come out through the air purge hole as air bubbles. Once no air bubbles are coming from the purge hole, place the plug back into the hole and tighten it until it is completely closed. Note: Because the air purge plug is tapered, there’s no need for Teflon tape to seal off the threads. 

Step 4 - Purge The Liquid From the Air Side of the Pump
After purging the oil side of the pump, the liquid side of the pump will need to be purged. Locate the discharge cap and loosen it without removing it entirely. Locate the supply valve and open it. Then, go back to the discharge cap and loosen it until the liquid begins to purge. Once all the liquid has been purged, tighten the discharge cap with a wrench. Once all air and liquid have been purged, the pump is ready to be primed. 

Step 5 - Prime The Pump
The easiest way to prime the pump, especially when handling corrosive chemicals, is to connect a T with a valve at the discharge with the outlet connecting to the calibration column. As long as there is a flooded suction coming down into the pump, gravity feed takes effect, and any air that is in the pump is purged out. After the pump is primed, check the rotation of the motor.

Step 6 - Check The Rotation of the Motor
After wiring the motor based on the schematic that is located on the label of the pump, check that the motor has a counterclockwise rotation by bumping (or turning the pump on and off very quickly, only once). Note: If the motor rotation is not counterclockwise, recheck the schematics on the label and adjust the wiring accordingly. Once the counterclockwise motor rotation is established, the pump can be started and checked.

Step 7 - Start & Check The Pump
Before operation, it’s important to heat the oil, remove any excess air that may have remained after purging and check for any issues. This is accomplished by running the pump in incremental flows. First, ensure that the micrometer dial is set at zero, and then start the motor and let the pump run for about five minutes. Then, increase the amount of flow (adjusting the micrometer dial) in increments, repeating the process of allowing the pump to run for about five to ten minutes and then setting the micrometer dial back to zero.  Note that one full rotation of the dial is 10% of the flow. Adjust the flow in increments of 30%, 60% and then 100%. Finally, at full flow, run the pump for about fifteen to twenty minutes. If there aren’t any issues, the hydraulic metering pump is ready for operation.

Following these steps will help ensure the optimal performance of Neptune hydraulic metering pumps in critical operations that require reliability, efficiency and safety. For a step-by-step demonstration by a Neptune expert, click here to watch the video. Visit our products page to learn more about the full range of Neptune hydraulic metering pumps.