Class A vs Class B – High Water Pressure Jetting Explained

If you operate a water jetter in Australia, understanding the difference between Class A and Class B high pressure water jetting equipment is an important part of choosing the right machine, training your operators and working safely.

One of the biggest misconceptions we hear is that the classification is determined by PSI alone.

It isn’t.

A 5,000 PSI machine is not automatically Class B, just as a lower-pressure machine is not automatically Class A. The classification takes into account both the operating pressure and the water flow rate of the system.

At Assassin Jetters, we work with plumbers, drain cleaners, contractors and maintenance teams across Sydney and Australia to help them choose, operate and maintain high pressure water jetting equipment.

According to Georgina Taylor, Business Leader at Assassin Jetters, understanding the difference should happen before you purchase a jetter – not after.

“People naturally focus on PSI when comparing jetters, but pressure is only one part of the equation. You need to look at pressure and flow together to understand what the machine can actually produce and which class it falls into.” — Georgina Taylor, Business Leader, Assassin Jetters

So, what actually separates a Class A jetter from a Class B jetter?

Let’s break it down.

What Is High Pressure Water Jetting?

High pressure water jetting uses pressurised water delivered through specialised pumps, hoses and nozzles for applications such as drain cleaning, pipe cleaning and surface cleaning.

For plumbers and drain cleaners, the combination of pressure and flow is particularly important.

In simple terms:

Pressure (PSI or bar) contributes to the cutting and cleaning force of the water.

Flow (litres per minute or LPM) determines how much water the machine can deliver.

Together, they determine the energy output of the jetting system.

You can read more about how these two factors affect jetter performance in our guide to pressure and flow.

What Is the Difference Between Class A and Class B Water Jetting?

Safe Work Australia defines the classes using bar litres per minute (bar L/min).

Class A High Pressure Water Jetting

A Class A system produces a maximum energy between:

800 and 5,600 bar litres per minute.

Class B High Pressure Water Jetting

A Class B system produces maximum energy:

Above 5,600 bar litres per minute.

This distinction is important because the potential hazards increase as the energy generated by the water jetting system increases.

The official definitions can be found in Safe Work Australia's Guide for Managing Risks from High Pressure Water Jetting.

Class A vs Class B at a Glance

Classification	Energy Output	General Meaning
Class A	800–5,600 bar L/min	Lower-energy high pressure water jetting system
Class B	Above 5,600 bar L/min	Higher-energy high pressure water jetting system

The important point is that PSI alone does not determine the classification.

You need the pressure and the flow rate.

“Two jetters can both be advertised as 5,000 PSI machines and still perform very differently. Flow matters. When we're helping someone choose a jetter, we're looking at the complete system and what they're actually going to use it for.” — Georgina Taylor

How Do You Calculate Whether a Jetter Is Class A or Class B?

To determine the classification, you first need the machine's pressure expressed in bar, rather than PSI.

As a general conversion:

1 bar ≈ 14.5 PSI

You can therefore approximately convert PSI to bar using:

PSI ÷ 14.5 = bar

Then calculate:

Pressure in bar × flow in litres per minute = bar L/min

For example, consider a jetter producing:

3,000 PSI @ 10 LPM

3,000 PSI is approximately 207 bar.

207 × 10 = 2,070 bar L/min

That falls within the Class A range.

Now compare that with:

5,000 PSI @ 21 LPM

5,000 PSI is approximately 345 bar.

345 × 21 = approximately 7,245 bar L/min.

That exceeds the 5,600 bar L/min threshold and therefore falls into Class B.

This is why simply looking at the PSI sticker on a machine does not tell the full story.

Real-World Class A vs Class B Jetter Examples

Here are some practical examples using common pressure and flow combinations.

Jetter Output	Approx. bar L/min	Classification
3,000 PSI @ 10 LPM	2,070	Class A
4,000 PSI @ 13 LPM	3,586	Class A
2,600 PSI @ 21 LPM	3,765	Class A
5,000 PSI @ 21 LPM	7,245	Class B
5,000 PSI @ 25 LPM	8,625	Class B

This makes the difference much easier to understand.

A 2,600 PSI machine producing 21 LPM remains within Class A, while increasing the combination to 5,000 PSI at 21 LPM takes the system well into Class B territory.

Is a 5,000 PSI Jetter Class B?

Not necessarily based on PSI alone.

However, many professional drain jetters combining 5,000 PSI with higher flow rates such as 21 or 25 LPM will exceed the 5,600 bar L/min Class B threshold.

For example:

5,000 PSI @ 21 LPM = approximately 7,245 bar L/min

5,000 PSI @ 25 LPM = approximately 8,625 bar L/min

Both examples exceed the Class B threshold.

That is why you should always check the complete machine specification rather than relying solely on its maximum PSI.

“When someone tells us they have a 5,000 PSI jetter, one of our next questions is going to be: ‘How many litres per minute?’ Without knowing the flow, you're missing a major part of the specification.” — Georgina Taylor

Why Does Class B Jetter Training Matter?

Class B equipment produces significant energy and needs to be treated accordingly.

High pressure water can cause serious injuries, and the risks associated with jetting aren't limited to the nozzle itself.

Operators need to understand issues including:

• safe machine operation;

• hose and fitting inspection;

• nozzle selection;

• hose restraint;

• appropriate PPE;

• exclusion zones and protecting bystanders;

• emergency procedures;

• safe start-up and shutdown;

• equipment condition and maintenance; and

• hazards specific to the worksite and application.

Assassin Jetters provides jetter training courses for operators who need to better understand the safe operation of their equipment.

For additional information, visit our Jetter Safety and Compliance Resources, where you can also access safety information and downloadable resources.

“Training isn't about ticking a box. A Class B jetter is a serious piece of equipment. Operators should understand what the machine is capable of, how to inspect it properly and what to do if something isn't right before they start jetting.” — Georgina Taylor

Class A Doesn't Mean 'No Risk'

This is another important distinction.

Being classified as Class A does not mean a machine is harmless.

Class A equipment still uses high pressure water and still needs to be operated correctly.

Operators should follow the manufacturer's instructions, workplace procedures and applicable safety requirements regardless of whether the equipment falls into Class A or Class B.

High pressure water can cause severe injury when equipment is used incorrectly or when components fail.

That is why safety should be considered across the entire jetting system – not just at the pump.

Your Jetter Is a Complete System

A professional drain jetter isn't simply an engine and pump.

The system includes components such as:

• engine or electric motor;

• high pressure pump;

• unloader and pressure controls;

• jetting hose;

• hose reels;

• quick couplings and fittings;

• nozzles;

• valves;

• safety equipment; and

• operator controls.

Every component needs to be suitable for the pressure, flow and application.

For example, your jetting hose needs to suit both the pressure and flow requirements of your machine.

A higher-flow machine generally requires a larger hose diameter to minimise unnecessary pressure loss and allow the system to perform correctly.

For a more detailed explanation, read our guide: Jetter Hose – Which Hose Should I Choose?.

Hose Restraint and High Pressure Water Jetting

Hose failure is another risk that needs to be considered when operating high pressure water equipment.

A hose or coupling failure can release considerable stored energy, which is why hose condition, correct fittings and appropriate restraints are important parts of a safe jetting setup.

Assassin Jetters provides additional information about hose restraint and other compliance considerations on our Jetter Safety page.

Operators should also inspect jetting hoses regularly for signs of:

• exposed reinforcement;

• cuts;

• kinks;

• damaged outer covers;

• corrosion;

• damaged couplings;

• leaks; or

• other deterioration.

If you're unsure whether a hose is safe, don't simply keep using it until it fails.

Have it inspected.

Choosing Between a Class A and Class B Jetter

The answer isn't simply that Class B is 'better'.

The right jetter depends on the work your business actually performs.

At Assassin Jetters, we consider factors such as the type and diameter of drains you're clearing, typical blockages, required hose length, vehicle space, available water supply, frequency of use and the accessories you need.

Our FAQ explains why we prefer to discuss the application before recommending a machine: Water Jetter FAQs.

A smaller Class A system may be appropriate for certain applications.

For businesses regularly tackling more demanding drain cleaning work, a higher-output Class B system may offer the performance required.

The important part is matching the machine to the work.

“The biggest jetter isn't automatically the best jetter for every plumber. We want to know what drains you're working on, what blockages you're dealing with, what vehicle it's going into and how you're going to use it. That's how you build a setup that actually works.” — Georgina Taylor

Pressure Isn't Everything: Why Flow Matters for Drain Cleaning

When comparing drain jetters, PSI tends to receive most of the attention.

But flow is extremely important in drain cleaning.

Pressure helps the nozzle attack a blockage.

Flow helps carry loosened material through the pipe.

The combination of the two influences how effectively the jetter can clear and clean the drain.

That is also why nozzle selection matters.

A nozzle needs to be correctly matched to the machine's available pressure and flow. Installing a random nozzle because the thread fits does not mean the system is correctly configured.

The hose diameter, hose length, nozzle configuration and pressure losses throughout the system all affect performance at the working end of the hose.

Buying a Water Jetter? Ask These Questions First

Before purchasing a high pressure drain jetter, make sure you know:

1. What is the maximum operating pressure?

2. What is the maximum flow rate in LPM?

3. Does that make the machine Class A or Class B?

4. What training is appropriate for the equipment and work?

5. What hose size should be used?

6. Are the nozzles correctly sized for the pump?

7. What safety equipment is included?

8. Who will service and repair the machine?

9. Are replacement parts readily available?

10. Will the machine suit the drains you actually work on?

These questions can be far more useful than simply asking:

“How many PSI does it have?”

Maintenance Is Part of Jetter Safety

Operator training is only one part of safe water jetting.

Your equipment also needs to be maintained.

Pumps, unloaders, hoses, couplings, reels, nozzles and safety systems are exposed to significant loads during normal operation.

Regular inspection can identify deterioration before it becomes a more serious problem.

Assassin Jetters recommends a first service on a new jetter at 50 operating hours, followed by servicing at least annually, with more frequent servicing appropriate for heavily used machines.

You can find more maintenance information in our Water Jetter FAQs.

Class A vs Class B High Water Pressure: Frequently Asked Questions

What makes a water jetter Class B?

A water jetting system is Class B when its maximum energy output exceeds 5,600 bar litres per minute.

Both pressure and flow therefore need to be considered.

What is a Class A water jetter?

A Class A high pressure water jetting system produces maximum energy between 800 and 5,600 bar litres per minute.

Is Class B determined by PSI?

No.

The classification considers the combination of pressure and flow, expressed as bar litres per minute.

Is 5,000 PSI Class B?

You cannot determine the classification from 5,000 PSI alone.

You also need the machine's flow rate.

For example, a jetter producing approximately 5,000 PSI @ 21 LPM produces roughly 7,245 bar L/min, placing it above the Class B threshold.

How do I calculate bar litres per minute?

First convert the machine's PSI to bar:

PSI ÷ approximately 14.5 = bar

Then:

bar × litres per minute = bar L/min

You can compare the result with the Class A and Class B thresholds.

Is Class A equipment safe?

Class A means the system produces less energy than a Class B system; it does not mean there are no hazards.

High pressure water equipment should always be operated according to appropriate procedures, training, manufacturer instructions and workplace safety requirements.

Where can I find official information about high pressure water jetting?

Safe Work Australia publishes the Guide for Managing Risks from High Pressure Water Jetting, which provides information on Class A and Class B systems and managing water jetting risks.

Need Help Understanding Your Jetter Classification?

If you aren't sure whether your existing jetter is Class A or Class B, don't guess based on the PSI.

Find the machine's rated:

PSI + litres per minute.

From there, its approximate energy output and classification can be determined.

Assassin Jetters works with professional water jetting equipment every day, from machine selection and custom jetter packages through to servicing, repairs, accessories and operator training.

Our team can help you understand the equipment you already own or choose a new system suited to the work your business performs.

Explore our Jetter Training Courses, visit our Jetter Safety and Compliance Resources, or contact Assassin Jetters to discuss your setup.

Assassin Jetters
Seven Hills, Western Sydney NSW
Phone: (02) 9674 9088

Because when you're dealing with high pressure water, knowing what your equipment is capable of isn't just about better performance.

It's about operating it safely, correctly and confidently.