Jet Tech
It's important to use the right language to describe our units. While technically our core products are ejectors and eductors, we will use the term "JET PUMP" to encompass "the entire style of pump(s) which use a motive fluid (air, steam or liquid) to create an internal vacuum and impart a motive force on an entrained fluid."
Below is the accepted standard terminology of the pump and piping industry for units in this class or style of general pumps. However in practice, we note a high degree of interchangeability of these terms by those who are not experts in the field.
How Annular and Concentric Jet Pumps Work!
First, let's discuss the differences between two basic types of Jet Pumps - the "Annual Jet Pump" and the "Concentric Jet Pump."
You should know that AN-JET manufactures both types of pumps, and for several different reasons. We will explore both deeper and differences will be more obvious as you learn about each type of Jet Pump.
These are not the only Jet Pump configurations can supply. AN-JET is constantly reviewing and inventing new application technologies to make your work safer, better, longer lasting and even cheaper wherever possible. Our innovation comes without sacrifice of durability or performance.
We know it can get rough out there when jobs shift daily. Across 30 years of engineering and field work, we:
"walk the talk."
Annular Jets: (See Above Drawing)
Basic Configuration: The motive force (air or liquid) enter the centerline section of the jet pump, either from the rear (as shown above) or from the side, curving to the centerline axis of the jet.
Advantages: Greatest motive effect on the entrained fluid (liquid or gas). Often the configuration of inlet to motive input is 90 degrees to the flow - a problem for some applications where maximum suction fluid flow is needed.
Disadvantages: The centerline placement of the motive nozzle can and does obstruct the size of material that can pass through the jet pump.
Fluid Mechanics: The Motive Force (air, gas or liquid) under pressure - exits a special orifice or nozzle along the centerline of the device. Motive Pressure is converted to kinetic energy (velocity) as it exists an orifice or nozzle. Velocity at normal operating pressures of say 80 PSI is normally “subsonic” (below Mach - the speed of sound), but can be made sonic (above Mach) by either increasing motive pressure substantially, or by using a special divergent nozzle. The Motive Force enters the interior Convergent Vacuum Section of the jet device focused into the narrower Mixing Section of the jet device. This flow creates in its wake the primary vacuum (or suction) within the device. The vacuum created is instantly felt at the Suction Inlet of the jet pump. The differential pressure within the device draws in and accelerate suction liquids into the Mixing Section - normally a smaller diameter tube or section. The two fluid mediums (motive fluid and suction fluid) mix in the Mixing Section and approach similar velocities. To convert the higher velocity flow into discharge pressure, a Divergent Section is applied. This Divergent Section uniformly converts the mixed velocities back to a final exit Discharge Pressure. The mixed fluids exit the Divergent Section by a typical hose, flange, or pipe connection. This configuration allows for an array of connection options including cam-lock, hose, flange, or ridged pipe connection. Most often a field movable jet will incorporate a discharge hose.
Peripheral Jets: (Above Drawing)
Basic Configuration: The motive force (air or liquid) enter the jet interior from the sides (as shown above). The Motive Force is aligned to be generally in line with or cross the centerline of the jet at the lowest possible angle to the centerline flow. These are the hardest to produce and often cost a bit more, but offer some great advantages including "clear throat performance."
Advantages: Most often the configuration of inlet to outlet is axial - meaning the flow moves without a change in fluid direction. Best design for passing larger solids, biomass, minerals and man made pelletized materials. The only limitation to the size of solid material that can pass through this jet pump is the clear throat dimension (internal diameter.) All AN-JET are designed with adjustable nozzles - meaning you can "fine tune the jet" for a given application or field condition. The controlling facts there are suction fluid density and motive pressure. Best jet application for sand pumping, treasure salvage, placer gold mining and others applications where clear throat is an advantage.
Disadvantages: Slightly less motive effect on the entrained fluid (liquid or gas) than an annular jet. Normally more complicated to manufacture and thus more expensive to purchase.
Fluid Mechanics: The Motive Force (air, gas or liquid) exits under pressure the peripheral orifice (as a single ring orifice or series of individual orifices) along the outer peripheral of the pump device. Same as with the Annual Jet, the Motive Pressure is converted to kinetic energy (velocity) as it exists an orifice or nozzle. Velocity at normal operating pressures of say 80 PSI is normally “subsonic” (below Mach - the speed of sound), but can only be made sonic (above Mach) by either increasing motive pressure substantially, or by incorporating a special divergent nozzle. As with the Annular Jet Pump, the Motive Force enters the interior Convergent Vacuum Section of the jet device focused into the narrower Mixing Section of the jet device. This flow creates in its wake the primary vacuum (or suction) within the device. The vacuum created is instantly felt at the Suction Inlet of the jet pump. The differential pressure within the device between atmospheric pressure and vacuum pressure "draws in and accelerates suction liquids into the Mixing Section . The Mixing Section is normally a smaller diameter tube or section after the Convergent Section of the pump. The two fluid mediums (motive fluid and suction fluid) mix in the Mixing Section and approach similar velocities. To convert the higher velocity flow into discharge pressure, a Divergent Section is applied, same as a Annular Jet Pump. This Divergent Section uniformly converts the mixed velocities back to a final exit Discharge Pressure. The mixed fluids exit the Divergent Section by a typical hose, flange, or pipe connection. This configuration allows for an array of connection options including cam-lock, hose, flange, or ridged pipe connection. Most often a field movable jet will incorporate a discharge hose.
AN-JET is known for its expertise in designing both types of jet pumps. We specialize in more difficult field applications of pumping entrained solids in a fluid - fluids containing minerals, solids, oil slurries and sand. For these types of non linear applications, using a Peripheral Jet Pump is optimum due to the inherent clear throat of the design - but an Annular Jet Pump will work equally well (sometimes better) when using nominal inlet screening or filtration. We have used both in the field and both work.
Case-In-Point. Our newest 2" Annular Jet Pump - Model# AJ-20FP-20FP-SS - shown below allows up to a 3/8" solid (such as gravel, sand, biomass, etc.) to flow straight through the pump. Adequate inlet filtration at 1/4" screen opening coupled with a maximum solids density of 20% in solution, allow for reliable certainty of flow with little to no clogging. Most often it is the operator who determines if clogging will occur as many factors come to play. However rare, let's talk about clogging more below to reduce its infrequent occurrence.
Do Jets Pumps Ever Get "Clogged?"
Yes, infrequently, but on occasion all types of jet pumps can get clogged.
Clogging occurs because of several factors including: loss or cycling of motive pressure, unexpected or reduced motive volume, excess slurry density, filtration oversize, operator failure and operator usage error. However, best jet pump selection, adequate sizing, proper motive pressure, good filtration, right operation all can eliminate most all problems - including clogging.
Most industrial applications are "install and forget" types of installations. They just run and run. In more difficult applications where changes in environment are routine, all performance considerations must be known and reviewed in advance. Once your application and field routines are known, it's rare to have any form of jet failure when operated within the confines of the designed jet pump envelope.
Consider this. In liquid -liquid jet pumps a semi-clean motive fluid flowing through the jet pump dilutes heavier slurries. If clean water is not available, sometimes the addition of water helps the heavy slurries move faster and with less clogging potential.
As long as you stay in the 20% range of suspended solids, the jet pump WILL pump.
Add-on Valves for Jet Pumps
We encourage the use of a "purging valve" on the output of the jet pump. This valve (typically a full flow ball valve) redirects the motive flow and pressure BACK towards the Suction Inlet. This internal reversal of flow normally clears the jet pump of most blockages or obstructions. This important valve is "a routine addition" to any slurry or sand pumping operation.
We also require for safety a quick acting "motive fluid shutoff valve" close to the unit so an operator can shut off all motive pressure rapidly in case of human or machinery danger, blown discharge hose or other field failure event.
At AN-JET,
"Safety is never an afterthought"
We hope this brief technical discussion has helped you understand more about the world of Jet Pumps, their use and helped you identify any remaining questions for your AN-JET Sales Representative.
They will work hard to give you complete confidence in application of our products to your selection and purchase details.
If we don't know the answer to a critical question, we'll find out the answer together.