How to pump grease from a Fluid-Bag

Useful information about best practices for pumping grease or other liquids from a Fluid-Bag

The viscosity of the liquid is a determining factor 

  • For low viscosity fluids the pumping from a Fluid-Bag is just like any other container (residue level might be better, contamination risk lower etc., but the actual pumping procedure is the same).

  • For high viscosity products there are a few important things to be aware of:

    • A Discharge Roller or Tau Xtractor is needed to bring the product down to the pump.
    • The Discharge Roller or Tau do not create a pressure to feed the pump.
    • It is the pump that must pull the product out of the container, so it is crucial that the pump in use can create a vacuum (suction).
    • It is equally vital that the container to pump connection is absolutely airtight. If there is an air leak, the product will not move. Fluid-Bag offers all the necessary adaptors.

  • The final pump selection is always done based on the requirements of the user, what the application is, what kind of set up it should fit into, what the liquid product is, the temperature, the piping etc.

  • The discharge speed for a certain product is solely depending on the pump and its capacity. The Discharge Roller or the Tau will follow the speed of the pump and the bag will become empty at that rate, be it then 20 minutes or 5 weeks.


Get started with some examples

To start with you can take a look at some previously used pump and equipment set-ups we have used for other customers. We present the 3 most common set-ups with Fluid-Bag containers and different pump models for grease applications. We also list which adaptors and additional equipment you will need in each case. Click on the banner below to go to the download page:

Semi Automatic Discharge Roller and pump set-ups

Pumping different types of Grease Products from Fluid-Bags

Fluid-Bag for NLGI 00 and 0 greases

These types of greases are often supplied in Fluid-Bags with 2” discharge pipe, or possibly in Fluid-Bags with 3” discharge pipe (in that case a flow control adaptor is included).

These greases are fairly liquid and can probably be pumped out of the bag without the need for discharging equipment such as a semi-automatic Discharge Roller or a Tau Xtractor. It is sufficient to simply stretch the inner container. This stretch will make the grease flow down to the pump and leave very little residue after the pumping is done.

Pump choice: since the grease is flowing down to the pump, there is no limitation on what kind of pump to use. The connection is most likely done with a short hose and a Camlock connection.

Fluid-Bag for NLGI 1, 2 and 3 greases

These greases require a semi-automatic Discharge Roller or a Tau Xtractor for the discharge. These greases are supplied in bags with a 3” outlet, possibly with a flow control adaptor included. The discharging equipment will bring the grease down to the pump and keep the bag tight, hindering the pump from “digging a hole” in the grease, causing possible cavitation. The discharging equipment will also “clean” the foils inside the inner container, leaving the lowest amount of residue comparing with other competing container systems.

Pump choice: the pump must be able to pull the grease out of the Fluid-Bag, so it must be able to create a vacuum. Piston pumps, progressive cavity pumps, diaphragm pumps are typically the best ones. The pump must be as close as possible to the bag to minimize the need of suction. A long hose will add a big flow resistance, and on the suction side of the pump this is not wanted as it will reduce the capacity.

A common misunderstanding is that the Discharge Roller will push the grease out of the container. This is not the case. The purpose of the Discharge Roller is to “clean” the foils to leave as little residue as possible. Another important action is to keep the bag tight, to prevent that the pump “digs a hole” in the grease and starts to cavitate.


The adaptor is an important item in the Fluid-Bag pumping. As mentioned already the connection between pump and bag must be airtight. Gaskets and threads in between these two must be in order. The safest way is to contact Fluid-Bag to get suggestion and order the adaptor(s).

Normally we need to know:

  • Size of the Fluid-Bag discharge pipe; 2”, 3” or 4”
  • Type of pump, brand, and model if you want to use an existing pump.


The pump information will give input to the following:

  • Is a wagon needed to move the pump in position to be connected to the bag?
  • What kind of adaptor is needed for this pump?
  • The size of the grease pump adaptor in case it is a drum pump with a pump tube. Based on the pump model we can find out the exact diameter of the pump tube. The grease pump adaptor must be exactly fitted to the pump tube to give an airtight connection. This pump will possibly also need a pump support and support sleeve on the Discharge Roller.


Fluid Bag pump picture 1

Fluid Bag pump Picture2

Fluid Bag pump Picture3

 Raasm pump with a male Camlock connected with 650062 + 406820 (female camlock Type D)

Fluid Bag pump Picture4

A drum pump with a pump tube inserted into the bag outlet. A pump support holds the pump, and a grease pump adaptor is the connection.


More information about suitable pumps and equipment for Fluid-Bag bulk containers:

We have prepared a more thorough form that you can fill in and send to us. The information in the form will help us suggest the best pump for your. Click here to get to the form for download