If you work with any of the critical mechanical applications found in the modern world - including mobile construction equipment, and fuel pumps for example - it is likely you also manage hydraulic systems. Because these systems use liquids in various forms to generate power, you know that the inherent pressure feature of hydraulics has to be managed properly.

In the best-case scenario, a lack of sufficient management of pressure levels in a system could lead to inferior output. In the worst cases, it could cause damage to equipment or physical harm to system operators. Hydraulic pressure gauges play a critical role in regulating pressure by monitoring levels in either a specified part or the entire system to ensure things are operating normally. 

So how do you know which pressure gauge will work best in your hydraulic system? Just know what you’re looking for and choose carefully! Sounds simple, right? As a pressure gauge product lead at Ashcroft - a recognized authority in temperature and pressure solutions - I have seen many scenarios where the wrong pressure gauges were selected and the impact that decision had on operations. 

In this article, you will learn about the five pressure gauge features I consider most important for hydraulic applications so you can be confident about selecting the best option to meet your specific needs. Let’s get started.

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1.    Resistance to Pressure Spikes 

There are many situations where you may be relying on hydraulics in unpredictable conditions such as in a construction loader hauling materials to and from uneven surfaces to a truck towing a vehicle traveling down a crowded highway. In these applications, an unexpected shock or force could quickly send pressure levels up by tens of thousands of psi. A malfunction or temporary slip in any part of a system could also cause a huge pressure spike.

Hydraulic applications deal with fluids, which means paying special attention to potential pressure hikes is critical. Unlike air, hydraulic fluid can’t be compressed, so pressure spikes in the system can increase four to five times over the normal operating pressure. If your pressure gauges aren’t adequately designed to manage this kind of fluctuation, it can lead to serious challenges with both efficiency and accuracy.

As you compare options for pressure gauges, consider the maximum capacity of each option to determine whether or not it aligns with your requirements.

2.    Ability to Withstand Temperature 

Hydraulic pressure is often used in environments with extreme or unpredictable temperatures. Think about offshore mining equipment operated near the floor of the ocean, or construction vehicles working in places with sub-zero weather conditions. In these cases, hydraulic systems create so much force that they generate a significant amount of heat on their own.

Because of the way temperature and pressure interact, changes in temperature can cause corresponding shifts in pressure levels. 

When comparing pressure gauges, make sure to check the device’s reference temperature for span calibration and the specific amount of offset to expect for a particular range. Also, consider a dry gauge or a liquid-filled gauge – the former style can usually be used at higher temperatures.

3.     Protection from Flutter and Vibration 

“Pointer flutter” occurs when consistent vibration or pulsation causes the indicator on a gauge to move very quickly back and forth between a small range on the dial. This in turn makes the gauge more difficult for an operator to read and interpret. There are many reasons why a hydraulic system might be emitting vibration or pulsations. It could be, from a loose connection or  a change in surrounding air pressure or temperature. 

Some degree of flutter isn’t necessarily a sign that a system is failing or malfunctioning. As a rule of thumb, if flutter is causing your gauge’s pointer to move more than 5% across the full range of the device, I suggest taking steps to address whatever is causing the external vibration or the application.

With that in mind, the pressure gauges have options like liquid fill, Plus!™ Performance, or FlutterGuard™ which helps dampen the movement to help save the gauge to reduce any potential damage on the movement and to help with readability by reducing or eliminating flutter issues. 

4.    Assembly and Composition

The material a pressure gauge is built from is a key factor in compatibility with hydraulic systems. Better quality materials mean a pressure sensor has a better chance of withstanding internal and external challenges. Remember, even an ordinary-sized pressure gauge for use in a hydraulic system is typically built from many different parts, including:

●    The bourdon tube which is the internal C-shaped or helical component that pressure acts on, creates a displacement that is used to get a pressure reading.

●    The external casing that houses the entire unit and helps protect it from physical damage that affects operation. This is sometimes called the housing or enclosure.

●    Sealing components like gaskets and O-rings that are used to connect various parts while maintaining an airtight seal, critical for accurate pressure readings.

I’ve found that stainless steel is the ideal option for a casing material. It is tough enough to withstand physical shock and can usually stand up to corrosive factors including moisture and extreme temperatures. Be sure the sealing components are also made of a durable enough material to work in your system and operating conditions. 

Another important assembly factor to consider is solid vs. open-front construction. When a pressure gauge is pushed beyond its capacity, it may physically rupture. A solid-front gauge is built with a rear blow-out plug to divert force and any fragmentary debris away from its operators. With an open-front gauge, there is a risk of physical injury or equipment damage in the event of a pressure overload.

5.    Compatible Mounting Options 

Because there are so many different types of pressure gauges, there are a significant number of ways to mount them. It’s relatively easy to find a gauge for a normal direct mount placement onto the specific pipe or area being measured, but you may need a more involved option like a panel mount or flange mount. Some of these will require additional equipment.

In the U.S. the standard for pressure gauge connection is expressed in National Pipe Thread (NPT).  Economical gauges with 1 ½ to 3 ½ in. dials typically offer 1/8 NPT to 1/4 NPT, while 4 ½ in. or larger dial sizes offer 1/4 NPT to 1/2 NPT. 

Two Hydraulic Pressure Gauges that Cover the Bases

Knowing the potential risks of working with hydraulic systems requires special care and attention, it is important to trust your pressure gauge to manage those risks and keep your operation running smoothly and safely. Two examples of gauges that check all the boxes above are the Ashcroft’s 8008S & 8009S. 

Our 800X line of pressure gauges is great for hydraulic systems because of their composition and flexibility. Both models are built from durable 316L stainless steel with laser-welded components for reliable performance. They are both CE and RoHS certified and meet EN837-1 and ASME B40.100 specifications for international use.

• The 8008S offers a tamper-proof gauge with a crimped ring
• The 8009S features a removable bayonet ring that allows operator access to the unit to make calibration adjustments

Both options offer a solid-front design if needed for additional safety.

Of course, there are still many different factors and options to consider – luckily, we’ve spent a lot of time thinking and writing about pressure gauges for use in all types of applications. 

We just scratched the surface. More information is available if you want to learn more. 

To learn more about pressure gauges and how to select the right one for your requirements, check out some of our other articles on the subject:

And, always feel free to contact us today to talk to one of our industry experts and get your questions answered.