Question 1

What is the difference between a jet pump and an eductor?

Accepted Answer

They are the same device — just different names used in different industries. "Jet pump" is common in general industrial use, while "eductor" is often used in chemical processing and tank applications. "Venturi pump" is another synonym. All refer to a device that uses a high-velocity motive fluid to entrain and pump a secondary fluid, with no moving parts.

Question 2

How does a jet pump work?

Accepted Answer

A high-pressure motive fluid (liquid, steam, or gas) is accelerated through a converging nozzle, creating a high-velocity jet. This jet passes through a suction chamber, creating a low-pressure zone that draws in the secondary fluid. Both fluids mix in the throat and exit through a diverging diffuser, where velocity converts back to pressure. The result: the secondary fluid is pumped without any moving parts.

Question 3

What fluids can be used as the motive fluid?

Accepted Answer

Common motive fluids include water, process liquids, steam, compressed air, and other gases. The motive fluid must be available at sufficient pressure to drive the eductor. In many tank mixing applications, the tank liquid itself is recirculated through the eductor as the motive fluid.

Question 4

What is the difference between a jet pump and a tank eductor?

Accepted Answer

A jet pump (inline eductor) is installed in a pipeline and is used to pump, transfer, or lift a fluid from one location to another. A tank eductor is installed inside a tank and is used to mix, heat, or circulate the tank contents. Both operate on the same Venturi principle but are designed for different mounting configurations and applications.

Question 5

How do I know which size eductor I need?

Accepted Answer

Sizing depends on your motive fluid pressure, required flow rate, suction lift or vacuum level, discharge head, and fluid properties. Use our online Sizing Calculator for a quick estimate, or fill out a Jet Pump or Tank Eductor Application Form for a precise engineering recommendation from our team.

Question 6

What materials are available?

Accepted Answer

Jet pumps are stocked in Carbon Steel, 316 Stainless Steel, and Bronze in sizes ½″–3″. Tank eductors are stocked in Carbon Steel and 316SS (⅜″–3″), and in PPL (Glass Reinforced Polypropylene) and PVDF (KYNAR®) for corrosive chemical service (¼″–1½″ MNPT). Special alloys such as Hastelloy, Alloy 20, and Titanium are available on request.

Question 7

Can I use a jet pump with corrosive chemicals?

Accepted Answer

Yes. For corrosive service, we offer 316 Stainless Steel, Hastelloy, Alloy 20, PPL (Polypropylene), and PVDF (KYNAR®). PVDF offers excellent resistance to oxidizing agents, halogens, and most acids and bases. Contact us with your specific chemical and concentration for a material recommendation.

Question 8

What is the maximum suction lift for a liquid jet pump?

Accepted Answer

Standard liquid jet pumps can achieve suction lifts up to 27 feet (approximately 11.7 PSI vacuum). Minimum NPSH required is 3 feet. For applications requiring greater suction lift, contact us for a custom sizing.

Question 9

How many tank eductors do I need for my tank?

Accepted Answer

It depends on tank shape, size, and turnover requirements. A single eductor is often sufficient for spherical or small cylindrical tanks. For tanks where the length-to-diameter ratio exceeds 2:1 (such as tank trucks), or for large tanks, multiple eductors are recommended. Our application form will help us determine the right quantity and placement.

Question 10

What is the mixing ratio for tank eductors?

Accepted Answer

When inlet pressure is in the 20–70 PSI range, tank eductors entrain approximately 4 gallons of tank contents for every 1 gallon of motive fluid — a 4:1 ratio. Outside this pressure range, the ratio drops to approximately 2.6:1. This means the total discharge volume is 4–5× the motive flow, providing highly efficient mixing.

Question 11

Can jet pumps handle solids or slurries?

Accepted Answer

Yes. Jet pumps are well-suited for handling slurries, sand, sludge, and suspended solids because they have no impellers or close-clearance parts to clog or wear. The large, open flow path allows solids to pass through freely. This makes them popular for sump cleaning, dredging, and sand/mud transfer.

Question 12

What vacuum levels can jet pumps achieve?

Accepted Answer

Using steam or air as the motive fluid, jet pumps can achieve vacuum levels down to 5 inches Hg Absolute (approximately 29 inches Hg vacuum). Liquid-motive eductors can achieve up to 29 inches Hg vacuum. The achievable vacuum depends on motive pressure and the specific model.

Question 13

What is the maximum temperature for tank heating eductors?

Accepted Answer

Tank heating eductors using direct steam injection should not be used to heat open-tank liquids above 140°F at atmospheric pressure. Exceeding this temperature risks uncondensed steam evolving from the liquid. For higher temperature requirements, contact us for alternative configurations.

Question 14

Do jet pumps require any maintenance?

Accepted Answer

Jet pumps and eductors have no moving parts, no seals, no packing glands, and require no lubrication. In most applications, they are essentially maintenance-free. Periodic inspection for wear or corrosion is recommended in abrasive or highly corrosive service. The nozzle and diffuser can be replaced if worn.

Question 15

How are tank eductors installed?

Accepted Answer

Tank eductors can be mounted in any position — horizontal, vertical, or angled. They are typically installed at the bottom of the tank and connected to a recirculating pump via a supply manifold. The discharge end should be aimed toward the most remote part of the tank. The suction end must be positioned away from walls to allow free flow of liquid into the suction openings.

Question 16

Can jet pumps run dry?

Accepted Answer

Yes — unlike centrifugal pumps, jet pumps will not be damaged by running without suction fluid. If no suction fluid is available, the eductor simply passes the motive fluid through to the discharge. This makes them ideal for intermittent or variable-flow applications.

Question 17

What causes steam hammer in tank heating eductors, and how do I prevent it?

Accepted Answer

Steam hammer occurs when steam condenses too rapidly, creating pressure waves. To prevent it, ensure the minimum absolute pressure of the eductor is at least twice the absolute pressure inside the tank at eductor depth. Proper steam pressure and eductor sizing are critical — our application form helps ensure correct selection.

Question 18

What sizes do you stock?

Accepted Answer

We maintain a large inventory for same-day shipment: Jet Pumps in ½″–3″ (Carbon Steel, 316SS, Bronze); Tank Eductors in ⅜″–3″ (Carbon Steel, 316SS); Plastic Tank Eductors in ¼″, ⅜″, ¾″, 1″, and 1½″ MNPT (PPL and PVDF). Special sizes and materials are available with lead times.

Question 19

Do you stock Penberthy replacement parts?

Accepted Answer

Yes. We stock direct replacements for Penberthy jet pumps and tank eductors, including Carbon Steel, Bronze, and 316SS jet pumps, and ¾″–3″ tank mixing and heating eductors. See our Penberthy Replacements page for details.

Question 20

How do I request a quote?

Accepted Answer

The fastest way is to fill out our Jet Pump Application Form or Tank Eductor Application Form — these give our engineers the information needed to recommend the right model and provide pricing. You can also call us at 1+201-419-6111 or use the Contact Us form.

Frequently Asked Questions

Basics

Selection & Sizing

Performance

Installation & Maintenance

Ordering & Availability

Still Have Questions?

Continue Your Research

Sizing Calculator

Product Selector Wizard

Request a Quote