Tag Archives: pump failure

who’s to blame?

By David Hollen, Technical Engineer

Frequently a customer will state that they have short pump lives and immediately the blame is placed on the pump. However, often it is not a pump problem at all, but rather a system or operational problem.

Generally, when someone mentions this it is not uncommon to associate the problem with the hydraulic conditions. In fact, oftentimes the issue is not on the liquid side of the pump at all, but instead it is a problem with the air supply.

There are two types of common air supply problems; contaminated or dirty air and air starvation. Just as we need clean air to live, so does a pump. If the pump is clogged with dirt and debris it will be starved for air and not perform properly.

The best way to keep your pump clean from dirty air is to install a filter regulator (Figure 1). A filter regulator is easy to install and provides the precise pressure control necessary to optimize pump performance and efficiency, at the same time preventing airline contaminates from reaching your pump.

Figure 1: Filter Regulator

Yamada offers a wide selection of filter regulators specifically selected for optimal performance with your pump (see chart).

Filter Regulator & Yamada Pump Chart

Filter Regulator Pump Series
FR-1, FR-1A NDP-5/15/20
FR-3, FR-3A NDP-25/32
FR-4, FR-4A NDP-40
FR-5, FR-5A NDP-50/80
FRL-2, FRL-2A DP-10, G15
FRL-4 XDP-40
FRL-5, FRL-5A XDP-50/80
A = auto drain

The photo below (Figure 3) is a diagram of a proper Yamada pump installation.

Figure 3: Yamada Pump Installation Diaphragm

The second main air side problem, air starvation, can be caused by several factors; a dirty air filter, a partially closed valve, an undersized airline/fitting or an undersized compressor.

The best way to check if you are experiencing air starvation is to observe the air pressure gauge mounted near the pump. If there is not any swing in the gauge needle when the pump strokes, then you have a very good air supply. A swing of 10% is acceptable. If you get a wide swing, such as 70 PSI to 40 PSI, then the air supply may not be adequate, and the pump is starving for air.

Yamada Filter Regulator Video

If you are not receiving the proper air supply from your filter regulator, start by cleaning the air filter and check that the valve is clear of debris. Additionally, make sure you have installed the proper size airline, connections and air compressor.

If, after taking the necessary steps, you continue to have performance issues, contact your Yamada distributor for further assistance.

Dave’s Corner: Shaft Cushions

Lately we have seen several pump failures due to improperly installed shaft cushions (p/n 770582). We have noticed that the problem occurs when a shaft cushion is installed in a pump that does not require it.

For instance, the shaft cushion is used on all NDP-40 and NDP-50 pumps with rubber diaphragms, including Santoprene® and Hytrel® elastomers. However, the shaft cushions are not to be used on NDP-40 and NDP-50 pumps with PTFE diaphragms or any NDP-80 series pump.

The purpose of the shaft cushion is to prevent the center disk from impacting the air chamber wall when operating at the far right of the performance curve. This isn’t an issue with the NDP-40 and NDP-50 pumps outfitted with PTFE diaphragms because the pumps are destroked and will not travel far enough to impact the chamber. This can, however, happen with the NDP-80 series pumps. A shaft cushion cannot be used because it will interfere with the center disk as it makes contact with the pilot valve.

Lastly, if you have a rebuilt NDP-80 pump and cannot get it to cycle, check to see if it was rebuilt (incorrectly) with shaft cushions. Below is a quick reference guide to follow when determining whether you can install shaft cushions in your pump.

shaft cushion