Motiv-Air-Torr Tee Type

The Motiv-Air-Torr® is a tee-type mini-eductor (Venturi eductor) that provides a compact, highly efficient solution to remote sampling of gases or liquids.

Our Venturi eductor has no moving parts, so it is maintenance free and optimized for minimal gas usage.

Uses of this miniature industrial aspirator, also know as a Venturi vacuum pump or eductor, include gas or liquid aspiration, fine solids dispersion, dilution, evacuation, and many other applications.

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Examples of the Motiv-Air-Torr

ASP-520-S-4316 Stainless steel with 1/4" union tee520-s-4
ASP-520-S-4M2316 Stainless steel with 1/4" branch tree with 1/8" MNPT threadasp-520-2-4m2
ASP-520-T-4Teflon with 1/4" union teeteflon

Our gas and air aspirators are used all over the world in gas & oil, petrochemical, pulp & paper, food and power industries for monitoring, analysis and environmental applications. Instrument manufacturers and analyzer system integrators utilize the Motiv-Air-Torr as an integral part of their sample system designs. With no moving parts the Motiv-Air-Torr is a maintenance-free, cost-effective alternative to sample pumps. And because of the optimized design, air (or nitrogen, argon, methane, …) usage is minimized, resulting in a highly efficient aspirator. Download the Information Sheet (PDF). Download the installation instructions (PDF)


  • Simple design
  • No moving parts
  • Easy to install
  • Very low to no maintenance
  • Can overcome back pressure
  • Inexpensive replacement for pump
  • Intrinsically safe
  • Very low capital cost and cost-of-ownership

How It Works

  • Draws samples through analytical instrument
  • Powered by pressurized gas or liquid
  • Vaccum generator
  • Installs on single point samples or multi-point manifolds
  • Recovers analyzed samples while using the fast loop to power the aspirator

Uses for the Motiv-Air-Torr® Venturi Eductor

Our gas and air aspirators are used all over the world in gas & oil, petrochemical, pulp & paper, food and power industries for monitoring, analysis and environmental applications. Some of the uses for this aspirator are listed below:

  • Educts remote samples of toxic, flammable or corrosive atmospheres for analysis
  • Monitor for oxygen depletion
  • Sample low or slightly negative pressure process lines or stack samples
  • For venting, mixing of gases, monitoring stacks, emissions, flues, pollution control, instrumentation, and medical applications
  • Can use process fluid as motive force and return the sample to the process
  • Minimize process fluid entering an analyzer shed for safety


Gas Phase

The charts below illustrate the performance characteristics typical of the Motiv-Air-Torr mini-eductors

Vacuum vs. Sample Flow at Motive Air Pressures

Vacuum vs. Sample Flow at Motive Air Pressures


Sample Flow vs. Motive Pressure ASP-520-X-4


Air Usage vs. Motive Pressure ASP-520-X-4


Liquid Phase

Liquid driven eductors are gaining greater acceptance and application as a reliable method of transporting liquid samples to process analyzers.  Whether driven by water or process fluid, designers are realizing their value and increasingly incorporating these ‘pumps’ in sample systems. Read more.

Advantages of Motiv-Air-Torr® mini-eductor

The following chart illustrates the efficiency of the Motiv-Air-Torr mini-eductor versus the performance from several competitors.  Our mini-eductor produces vacuum at significantly lower operating pressures which reduces the amount of motive air used.  In fact for many sampling devices and continuous analyzers, the motive pressure can be run at 5-10 psig to produce the sample flow and sample lag time required for reliable analyses.

Motiv-Air-Torr mini eductor performance

Installation “Best Practices”

For installation details for the Motiv-Air-Torr® eductor, click here.
Typical installations are illustrated in the following drawings.

  • Normal installation – To sample a low or slightly negative pressure sample or one at atmospheric pressure, refer to illustration “A” below.  Be sure to place the needle valve after the rotometer.
  • Sample mixing and dilution – A recommended method to install an educator for mixing at a given ratio is shown in illustration “B”.
  • Returning sample to process – For a pressurized process the process sample can be used as the motive force.  The sample can be returned to process at a point with lower pressure or alternatively sent to exhaust or a flare.

Venturi eductor Motiv-Air-Torr installations

Back Pressure Applications

An eductor is used to draw samples from remote, positive or negative pressure sample points and are either vented, returned to the process or sent to a flare. Often there is a backpressure at the exhaust. Compensation for this condition requires that the motive pressure be increased. Below are curves that illustrate flow capacities vs motive pressure at different back pressures.

Backpressure/flow rate curves

Backpressure/flow rate curves: The above illustrates the sample or vacuum flow rate vs motive force for three different back pressures at the exhaust. This data is useful when it is necessary to return the sample to the process or to send it to a flare header. The flow rates are shown for 5 psig (blue) backpressure at the exhaust, 10 psig (red) backpressure and 15 psig (green) backpressure. These curves shift significantly higher when an elevated sample pressure exists (see below).

Sample flow rate at 2 sample pressures

This plot illustrates the effect of an elevated sample pressure while experiencing a 15 psig backpressure at the exhaust (atmospheric sample pressure, red; 5 psig elevated sample pressure, blue).  The sample flow rate is significantly increased with the elevated sample pressure.

Download the Motiv-Air-Torr Back Pressure Performance brochure (PDF).

How to Order

Contact us at or or call 423-967-2019 or fill out a Request a Quote form and we will be in touch with you shortly.