Products Inert Small Port Nitrogen Purge Hopper
Rheo Inerting equipment Small Port Nitrogen Purge Hopper

Small Port Nitrogen Purge Hopper

The Small Port Nitrogen Purge Hopper facilitates the addition of large quantities of powders or other solids through small vessel ports. This design can be configured to facilitate the charging of bag stock, bulk sacks, or drums.

Maintaining Low Levels of Oxygen

The Rheo Small Port Nitrogen Purge Hopper serves as an engineering control to help maintain low oxygen concentrations within a process vessel during the manual addition of solids. This device utilizes a safe, pneumatically-powered butterfly valve that reduces the amount of time the tank is opened to the room environment. Split valve technology can also be used instead of the pneumatically-powered butterfly valve for high-containment applications. A full perimeter annular ring injects nitrogen at dual flow rates to dilute oxygen concentrations in the manway region of the tank. This engineered system has proven to maintain oxygen levels to below 5% for the duration of a charging process.

Diagram showing the flow of materials through the Small Port Nitrogen Purge Hopper

Tank Dynamics

In order to reduce the risk of deflagration within a process tank, an inert gas must be injected in the correct quantity, location, and time of the product transfer. Understanding the tank dynamics of each application is critical to implementing the best engineering control for this process. Existing nitrogen blanketing systems frequently do not apply the gas at the correct quantities, location, or timing during the solids addition process. This results in elevated oxygen concentrations in the manway region of the tank which increases the likelihood of a deflagration near the chemical operator.

Our inerting systems provide an effective control to reduce and maintain oxygen concentrations during the solids charging process. The dual rate injection system is adjustable and can be integrated with an oxygen level sensor to provide a precise control system.

The two figures below illustrate how a properly designed inerting system can change the tank dynamics and reduce the risk of  deflagration. Figure 1 demonstrates a common tank system that allows elevated oxygen levels near the manway region during the solids addition process. All three components of the fire triangle [shown in figure 3 below] are established in this scenario. The entrained air delivers oxygen to the headspace of the tank and mixes with the dry dust and solvent vapors. Static charge can generate the energy to ignite this volatile mixture resulting in a dangerous deflagration event, injuring the chemical operator and causing significant equipment damage. Figure 2 shows a tank where the inert gas is added at the proper quantity, location, and timing of a solids addition process. A properly located O2 sensor can provide accurate O2 concentrations to confirm a safe work environment.

A steel grate adding safety in Rheo' Small Port Nitrogen Purge Hopper


Stainless steel grating prevents large objects from falling in the hopper opening and eliminates the potential finger and hand hazards created by a powered butterfly valve system.


A variety of options are available for the Rheo Small Port Nitrogen Purge Hopper to ensure the final product meets the application needs. The following are a selection of some of the options available:

  • Product Grates/Cross Bars
  • Grounding Tabs
  • Bag Landing Table
  • Custom Manway Adapters
  • Mobile Carts
  • Removable Gravity Sealing Lids

Different options for the Rheo' Small Port Nitrogen Purge Hopper

Mobile Small Port Nitrogen Purge Hopper - stainless steel allows for easy cleaning.


The Rheo Small Port Nitrogen Purge Hopper is built from stainless steel components and can be fully disassembled.  The hopper can be fully washed down with water or light cleaning agent.  The integrated Ventilation Sleeve has a removable cover that provides wipe-down access to all surfaces of the sleeve.

Dust and Vapor Control

By utilizing the full perimeter Ventilation Sleeve option, this fully engineered system will significantly reduce fugitive dust and vapors that often occur during the process of openly transferring solids into a tank.

The addition of a ventilation screen on the Small Port Nitrogen Purge Hopper prevents fugitive dust and vapors

Engineering drawings of the Rheo' Small Port Nitrogen Purge Hopper


The Rheo engineering process allows this technology to be applied to virtually any application and process. Please contact your local representative for a list of custom options that can be added to the core charge hopper design.

Utility Recommendations

  • Single hose nitrogen connection provides pneumatic power to the valve as well as the nitrogen flow for the process.
  • Recommended Nitrogen Addition Rate (varies depending on application): 75 PSI [5 bar] static pressure; 300 SCFH [140 LPM] flow rate.
  • Recommended Local Exhaust: 400 SCFM [190 L/s]; 2.5 inches WC [6.2 millibar] static pressure.

Single hose nitrogen connection

Rheo' hand control for Small Port Nitrogen Purge Hopper


  • Hand control (or optional foot control) for the pneumatic valve.
  • Control activation increases nitrogen flow rate into the vessel in a nitrogen “blast”.
  • When controls are not activated, nitrogen enters the vessel at a slow flow “bleed” rate.
  • Both nitrogen “blast” and “bleed” rates are controlled independently with panel mount flow controls and can be adjusted.

Surface Finish

  • Rheo offers several different surface finish options to fit your application needs.

    Visit our GMP Compliance page to learn more.

Rheo offers multiple surface finished for GMP compliance. See the options side by side.