The Uses and Functions of Digital Pressure Gauges
Next to temperature, pressure is probably the most common measurement taken for any sort of industrial or commercial application. Even at home, you may find yourself measuring pressure in order to properly calibrate your boiler system or ensure optimum operation of your car tires. A digital pressure gauge is the simplest, most straightforward way of measuring and displaying pressure for most uses. While other pressure sensors typically transmit electrical signals to a remote location for the purpose of recording and later analyzing data, digital gauges display the information immediately and locally in a direct, easy to understand readout. In order to best outline the functionality of digital pressure gauges, I should first proffer a brief rundown on how pressure works.
“Pressure” is a general term used to describe the force exerted on a given unit of area. Pressure can either be static, when measuring a gas or liquid, which is sitting still, or dynamic, when measuring a gas or liquid in motion. (A hydrostatic pressure gauge, for example, could be used to measure the pressure in a water tank). When talking about liquids, pressure can be measured either as “feet of head,” which is the theoretical height to which a liquid would rise in a container, or “pounds per square inch,” which is the aforementioned force exerted per unit of surface area. For most commercial and industrial applications, the gauge readout will be in pounds per square inch, or “psi” for short. For example, if I were to attach a gauge to any of the tires on my car right now, the readout would probably be around 32 psi, which means 32 pounds of force per square inch of tire surface.
Digital gauges and analog gauges function a little differently and thus have slightly different applications. Analog gauges usually rely on an internal mechanical structure responding to changes in pressure by either expanding or contracting. A needle is attached to this structure and moves along a set of numbers on a dial to indicate pressure. Digital gauges, on the other hand, use more advanced microprocessors and sensors and are capable of delivering extremely accurate measurements on a user-friendly digital readout. For these sorts of gauges, changes in pressure effect changes in the electrical resistivity of a metal or semiconductor, which is then reflected onto the gauge.
Since they’re easy to read and can be calibrated to display essentially any pressure range with extreme accuracy, digital pressure gauges are useful for an incredibly wide variety of commercial and industrial functions. Common applications for these devices include any form of mechanical engineering, generalized service operations, pneumatic testing (air pressure), hydraulics — the list really does go on. The readout units can even be customized based on location, usage, or even just personal preference, so that the user never needs to calculate conversions manually.
Digital gauges boast a whole host of other advantages over their analog counterparts as well.
-They’re easy to re-range: they can be quickly and simply calibrated to display pressure in any range. Whether you’re using a hydrostatic pressure gauge to measure the immense amount of pressure in a 75 foot tall water standpipe or you want to measure the relatively tiny amount of pressure exerted by a small gas leak, you can adjust your gauge to reflect any range of pressure.
-They have steady readouts in high vibration applications: for any mechanical or hydraulic applications where a pipe or piece of machinery vibrates as it exerts dynamic pressure, an analog gauge will be difficult to read and might not even give an accurate reflection. A digital gauge, on the other hand, will continue to give an accurate measurement even in situations where the machinery is subject to heavy vibration.
-They require no operator interpretation: analog gauges require the operator to personally calculate or even estimate pressure readouts from an archaic dial setup. This can be especially difficult and lead to especially inaccurate results in low-pressure applications, but can just as easily result in operator error at any pressure range. A digital gauge won’t have that problem. These gauges display a simple number which is not subject to interpretation or estimation of any kind, which allows an operator to much more easily ensure perfect accuracy of his or her reading.
-They’re far more durable: certain applications where you’ll need to measure pressure might have large spikes in pressure ratings. For example, shutting a valve too quickly or powering down a water pump too fast might produce “water hammer,” which is an immediate and powerful surge in pressure. The construction of analog gauges renders them structurally vulnerable to these sorts of pressure spikes, which can end up damaging or even destroying the equipment over time. A digital gauge won’t have that problem. A digital hydrostatic pressure gauge, for example, will easily be able to deal with the pressure differential created by water hammer and continue to give an accurate readout.
Digital gauges aren’t perfect, however. They do have two minor drawbacks in their application that I feel it’s only fair to mention.
-They require power: analog gauges don’t rely on electricity, so they can function without an external source of power. The same isn’t true of digital. With a digital gauge, you’ll need to provide a form of electricity, whether by battery (as is most common) or by other means such as solar.
-Analog gauges are slightly more useful in highly variable pressure situations: it’s a little bit easier to watch a needle bounce back and forth to get a general sense of rapid pressure changes than to watch numbers quickly change on a screen.
For my own personal pressure measurement needs, I always go digital. Whether at work at my water treatment plant, for the tires on my car, or for my SCUBA equipment, I prefer the ease and versatility of digital in almost all applications. Hopefully now you have a better understanding of the supremacy of the digital gauge!