Pressure Measurement:Gauges, Innovation, and Why It Matters 

Anyone who’s opened a can of soda after shaking it knows firsthand the conceptual impact of pressure. But how many of us have ever actually considered the importance of pressure measurement in modern industry? We suspect not many have, which is why we do: Pressure management is our business. 

In April 2010, the Deepwater Horizon oilrig disaster poignantly demonstrated the importance of accurately monitoring and measuring pressure. Before the explosion and during a negative pressure test on the Macondo well, two pressure gauges delivered two very different results: one indicated “no pressure” while another indicated pressure building. Amidst disagreement on the results, the test was redone; by 8 p.m., the crew and BP representatives aboard agreed that the well was stable. As they sealed the well, working quickly, Joseph Keith recalls feeling uneasy. His role, to monitor gauges that detect blowouts, is a crucial one. No leaking was noticed. But from 8:50 p.m. on, oil and gas were leaking into the well, and pressure built. At 9:47, the first explosion rocked the rig, the beginning of what would become known as the U.S.’s greatest oil disaster. 

From upstream oil & gas extraction to downstream processing, from balancing reactor temperatures with precise pressure application in chemical plants to maximizing cogeneration opportunity through high-pressure boilers in water treatment facilities—pressure measurement is a vital component in successful industrial operations.

Pressure: What It Is & How We Measure ItPressure is simply the force acting upon a unit of area. But the force on any solid surface does not apply to a single point on that surface, but rather is spread equally across the entire surface. This means the pressure depends not only on the level of

compression of the media, but also on the surface-area size. 

There are three kinds of pressure: fluid, absolute, and gauge. Fluid pressure is the measure of force per unit area exerted by a fluid (gas or liquid). Absolute pressure is the absolute value of the force per unit area exerted on a surface by a fluid, meaning that it is the difference between the pressure at a point in a fluid and the absolute zero of pressure (a complete vacuum). Gauge pressure is the measure of the difference between absolute pressure and atmospheric pressure, which varies based on altitude, weather, and ambient temperature; pressure gauges read differently at different levels of elevation. While a normal pressure gauge reads zero (45psi) at a certain elevation, it will read 14.5psi at sea level. This can make for a complex process of analysis when dealing with massive systems that cover multiple elevations, or several thousand feet of piping. 

When we talk about pressure measurement, it’s important to also talk about what reference the pressure is related to. In the U.S., we specify pressure in terms of pounds/square inch absolute (psia) or pounds/square inch gauge (psig). Negative gauge pressure is a vacuum, the measurement of the amount by which the local atmospheric pressure exceeds the absolute pressure; a perfect vacuum equals zero absolute pressure. Differential pressure, a common measurement in industrial applications, is the difference between two unknown pressures. 

The Evolution of MeasurementModern tools for measuring pressure emerged in the mid-19th century with the introduction of the Bourdon tube, still widely employed today to determine static pressure. The mechanism has not changed dramatically: the tool generally contains a curved tube, open to pressure input on one end and coupled to an indicator needle on the other.

Technologies have evolved to meet the needs of specific applications; today’s gauges can be specialized with all-welded, stainless steel construction for corrosive media;transmitters for hybrid gauge-data collection applications; diaphragm seals to provide longer lives for pressure gauges in harsh environments; sub-sea construction that allows for deep-sea (10,000 feet) applications; and highly accurate test gauges for laboratory uses. These integrated technologies allow users to take better readings, collect more thorough data, and operate more safely and efficiently in their target-specific environments. 

While the basic technology has changed little since its inception, industry leaders continue to refine, rethink, and reinvent the modern pressure gauge and its offshoots. WIKA Instrument Corporation, an innovator in gauge technology for more than 60 years, makes gauges more robust, reliable, and smart to meet ever-evolving industrial needs.

Is a Pressure Gauge Important to Everyday Operations? 

A pressure gauge is a common component in operations from various industries across the world. But not every gauge is created equally or made for every situation. WIKA Instrument LP has been on the forefront of innovation and quality for pressure gauges and pressure instruments for over 60 years, making us the pressure gauge expert for diverse industries and applications. Gauges with bourdon tubes are the most common pressure measuring devices used today. They combine a high grade of measuring technology, simple operation, ruggedness and flexibility with the advantages of industrial and cost-effective production. Needing no external power supply, bourdon tube gauges are the best choice for most applications. Pressure gauges are crucial components of most processing systems. In these environments, a pressure gauge needs to be reliable, accurate and easy to read to help prevent failure in everyday operations. Therefore, how a gauge is constructed and tested is extremely important for reliability, safety and peace-of-mind. After all, failures can cost time, money and productivity loss. Applications for gauges with a bourdon tube range from highly automated chemical processes, such as, refineries and petrochemical processing, tohydraulic and pneumatic installations. These types of gauges can also be found at all critical

process monitoring and safety points in today’s energy industries, from exploration wells and petrochemical plants, to power stations andwastewater operations.

What Happens When a Pressure Gauge Fails?

Whatever various forms and materials they use, a pressure gauge is designed to measure pressure from gases, liquids, vapors or solid bodies in many applications and industries. Due to the volatile nature some of these sources can take, pressure gauges and pressure instruments can fail for a multitude of reasons. Protecting and inspecting pressure instruments on a regular basis will help prevent failure and keep operations running smoothly. Through WIKA’s FAST Instrument Audits, we have identified the top reasons why a pressure gauge may fail. eLearning: Best Practices- Top Reasons Why Gauges Fail

Types of Pressure Gauges

A commercial pressure gauge is perfect for utility, general-purpose applications typically found in HVAC, refrigeration, ventilation and food and beverage industries as well as for OEM and end user applications. WIKA manufacturers a line of commercial pressure gauges suited for all your needs. Industrial pressure gauges are stainless steel gauges designed for the oil and gas, alternative fuels, chemical manufacturing, petrochemical and mobile hydraulics industries. An industrial pressure gauge is suitable for media that will not obstruct the pressure system.Industrial pressure gauges, WIKA’s most extensive product line, are designed to meet all your pressure measurement needs. Process pressure gauges protect against extreme environments, like in oil, gas and petrochemical industries, which face system vibration, pulsation, pressure spikes and corrosion. WIKA manufacturers a complete line of process pressure gauges for all your processing, oil and gas and chemical applications. Low pressure gauges are suitable for corrosive environments and gaseous or liquid media that will not obstruct the pressure system. WIKA’s low pressure gauges are suitable for chemical, petrochemical, plant construction, pneumatic systems and cleanrooms. Sealgauges are a pressure gauge combined with a diaphragm seal isolator and are designed to eliminate potential leak paths. WIKA’s Sealgauges are suitable for sanitary, chemical, petrochemical, pharmaceutical and process industries. High precision test gauges are designed for calibration and testing laboratories. These highly accurate test gauges are suitable for corrosive and industrial applications. WIKA’s high precision test gauges are intended for pressure monitoring panels, gaseous or liquid media that will not obstruct the pressure system or attack copper alloy parts and process industry applications. Differential gauges and duplex pressure gauges are designed for the oil and gas, alternative fuels, chemical, HVAC, refrigeration and air handling industries. Differential pressure and duplex pressure gauges are for measuring two applied pressures; high and low pressure and static process pressures. WIKA’sdifferential and duplex gauges are suitable for corrosive environments with liquid or gaseous media, cryogenic gases and when separation of media is required. Absolute pressure gauges measure absolute pressure without the effect of barometric pressure variation and are used when monitoring condensation pressures and vapor pressures of liquids. WIKA’s absolute pressure gauges are suitable industries and applications with corrosive environments and gaseous and liquid media.

The importance of pressure

G'day! How's the job going? Good I hope!

If you've got a few minutes to spare I'd like to stress the importance of pressure, flow rate and velocity when it comes to water sources and installing irrigation systems.

Pressure

Pressure is the energy used (and required) to deliver water through pipes to its final destination. In most cases we are talking about the pressure contained within pipes in an irrigation system.

Pressure is measured in kilopascals (kPa) or pounds per square inch (PSI)

Pressure can come in two forms: static or dynamic:

Static pressure is the outward force exerted by water when it is sitting in pipes, not going anywhere.

Dynamic pressure is the force exerted by water when it is flowing through pipes.

Correct pressure is important because too much can cause damage to pipes or result in losses due to small droplets being produced that are more susceptible to wind drift. Not enough will result in the inability to deliver water in the system.

Pipes, valves and fittings in a system all resist the movement of water through them to some degree. This results in what is known as friction loss. These losses need to be taken into account in order to deliver the water at the correct pressure to the emitters.

Most systems are designed to stand specific pressures where the speed (velocity) of water travelling through a system should not exceed 1.5 metres per second. Most manufacturers supply information with regards to the correct pressure requirements for their components.

Often people make the mistake of mixing up pressure and flow and getting these two terms confused. It must be stated that flow and pressure, while related in an irrigation system, must be kept as separate entities and understood as such.

Flow rate

Flow rate is the volume of water available or that can be carried, within an irrigation system.

Flow rate is measured in Litres per minute (LPM), Litres per hour (LPH) or Gallons per minute (GPM).

The quantity of water required to be moved is important when selecting pipes for an irrigation system.

When choosing pipe sizes for an irrigation system, cost should not be the motivating factor.

Pipes in an irrigation system should be sized according to good hydraulic practice.

The volume of water that the pipe is required to carry determines pipe size. Pressure losses (and gains) must also be taken into account when sizing pipes for larger systems.

The class of pipe (PN) that should be used in a given situation is determined by the working pressure of the system. When dealing with live main lines, static pressure is the determining factor for pipe class.

When sizing pipes it is critical that the velocity (speed) of the water does not exceed 1.5 metres per second (m/s).

A simple method for sizing pipes is to use the flow rate method. Generally if this method is followed and expectations are realistic, then pressure losses throughout the system will be acceptable.

Pipe Size (mm) Maximum flow (Litres per minute [LPM])PN9 PN12

  3665 60

135 125215 200465 440

Please note that US gallons differ to Australian gallons as:

 0.83270 Australian Gallons

Velocity and speed

When water passes through pipes, the pressure that pushes the water through that pipe determines the speed that the column of water travels at. Velocity is the speed that water travels through a pipe.

Velocity is measured in metres per second (m/s).

Velocities of water through irrigation pipes should be kept at around 1.5 metres per second.

Pipe and fitting specifications must be matched to the volume and pressure of water intended to flow through them. If the volume and pressure is greater than specified, pipes and fittings will wear, eventually causing the failure of these components.

Nearly all manufacturers have specifications for their irrigation components, which include pipes, valves, sprinklers and fittings. It is therefore important to follow these specifications and charts to establish good results and create a system that does not fail because of excessive turbulence and water hammer (among other problems).

Take a look at the specifications that you'll receive when you use the 12 Series sprinkler emitters from The TORO® Company, Australia. Take note of the Pressure and Flow rate columns.

| Back to Roy |

M

mportance of Pressure Measuring DevicesBy Nazima Golamaully  |   Submitted On July 27, 2010

   0 1

Most of our industrial mechanical systems are run through hydraulic pressure. For example you might have seen huge hydraulic press in some industrial units which are used to press different items. These are run by hydraulic pressure. Similarly, you may have seen the car lifters in motor workshop or motor service pumps. These hydraulic lifters can lift the large forks to a desirable height. The mechanic thus lifts your vehicle up to desired height for different maintenance jobs. This elevated position of your car enables him to work on the lower body of the vehicle which he cannot approach without lifting the vehicle to a certain height.

Also you may have seen some kinds of air pumps. Electrical motors are mounted on the top of ironic cylindrical body. Air is filled in the tank with the help of electric motor which enable pump to work. The cylinder is made up of iron and the edges are electronically welded. Each cylinder has its specific capacity to accommodate air pressure. To judge that capacity of cylinder, some type of gauge is used which is known as hydraulic measuring equipment. This device helps you fill the cylinder to a specific level by viewing reading from the gauge.

All the above examples explain importance of pressure measuring hydraulic gauges. If there were no such instruments installed with the

above set ups, you could not be able to judge the air pressure thus leading to some unwanted incidence. A hydraulic gauge is usually a small round shaped instrument which is equipped with a dial and one or two needles pointing to different levels mentioned on the dial. The pointing needles move with increasing pressure and thus you can judge the inner pressure. There are a number of hydraulic pressure measuring equipments available in the market. You can select one according to requirement of your job.

If you want to know more about digital height gauge [http://www.digitalheightgauge.net] and hydraulic pressure gauge [http://www.digitalheightgauge.net/hydraulicpressuregauge.php] please visit our website.

Article Source: http://EzineArticles.com/?expert=Nazima_Golamaully

It is time to know about pressure measurement..

    In general, pressure is represented as force per unit area. The measurement of pressure is one of the most important measurements, as it is used in almost all industries. Some important appilications of pressure measurement is listed.

1. The pressure of steam in a bolier is measured for ensuring safe operating condition of the boiler.2. Pressure measurement is done in continous processing industries such as manufacturing and chemical industries.3. Pressure measurement helps in determining the liquid level in tanks and containers.4. Pressure measurement helps in determining the density of liquids.5. In many flow meter (such as venturimeter, orifice meter, flow nozzle, etc.,) pressure measurement serves as an indication of flow rate.6. Measurement of pressure change becomes an indication of temperature (as used in pressure thermometers-fluid expansion type).7. Apart from this, pressure measurement is also required in day-to-day situations such as maintaining optimal pressure in tubes of vehicle tyres.

Definition of pressure:

            Pressure is the force exerted by a medium (fliud) on a unit area due to the interaction of fluid particles amongst themselves.

The following are the terms related to pressure namely:1. atomspheric pressure.2. Absolute pressure.3. Gauge pressure.4. Vacuum pressure (Rare fraction or negative pressure).5. Static pressure.6. Total or stagnation pressure.7. Dynamic or impact or velocity pressure.

The next post will describe in detail about the above terms.