Some vane pump manufacturers frequently blitz trade magazines with articles touting their “superior hydraulic efficiency”. Don’t buy it.
Since stretching the truth isn’t limited to politics Roper thought that they’d spend some time separating pump fact from pump fiction.
Some vane pump manufacturers frequently blitz trade magazines with articles touting their “superior hydraulic efficiency”. Don’t buy it. Their argument is that since the vanes rub on the case, there isn’t any “slip”. The one thing that they fail to mention though is the relatively high amount of slip that occurs on both ends of the pump between the rotor and side plates. Roper’s helical gear pump has a natural action that pushes the gears against each other and forces one towards the face plate and the other towards the backplate.
This reduces the amount of slip along the sides of the pump. Those of you with old vane pump catalogues will see performance curves that include a slip curve. Several years ago one of the larger manufactures eliminated the slip curves and only provided curves at specific viscosity points and pressures. The slip is now “built-in” to the actual flow curve and (hopefully for them) invisible. Roper could do that too but they believe it’s more important to provide accurate tools needed to size the pump correctly.
A few years ago Roper added 2 new pump sizes to the 3600 family that specifically address flow rates versus one of the most common 3” vane pumps in the market. Roper’s models 3632 and 3643 simply out-pump this vane pump. (See graph above). On top of that in most cases the 3632 is less expensive than a 3” vane pump and in virtually all cases more forgiving in tough applications.