Another PSI Sighting: Pressure Shows Up Everywhere

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you.

Another PSI Sighting: Pressure Shows Up Everywhere

While I could be more sensitive than many other people, any indication of the need to measure and/or control pressure in everyday situations usually catches my attention. A recent observation was the number on a neighborhood fire hydrant – in big letters it stated 200 psi. It turns that this is a common working pressure design criteria for residential fire hydrants.

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Conducting flow and pressure testing measurements require a pitot gauge and a fire hydrant cap gauge. Pressure measurements on fire hydrants are performed primarily using analog gauges with a 0 to 300 psi range although digital instruments do exist with one digital gauge specifying 0.5% accuracy. Static pressure is the normal pressure existing on a system before the hydrant flow valve is opened. Local requirements vary but in one case, normal minimum water pressure in a distribution system cannot be below 35 psi when a fire hydrant is opened downstream and the minimum water pressure (residual psi) cannot be below 20 psi. Observed pressure requirements include: 75 psi for larger cities and 50 psi for smaller cities.

In addition to the pressure range and accuracy, environmental aspects for a fire hydrant pressure sensor include the ability to withstand the contact of water and possibly other materials. Properly specifying the “designed for” and other operating pressures and environmental requirements are just the beginning of getting the right pressure sensors for testing fire hydrants or measuring the pressure of any flowing/static liquid.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Dan DeFalco, Marketing Manager, All Sensors Corporation (ddefalco@allsensors.com)

What does a psi matter anyway?

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll look at why a PSI or two matters.

What does a psi matter anyway?

Underinflated footballs created a viral controversy before Super Bowl 2015.  Measurements of air pressure of 10.5 pounds per square inch (psi) instead of the minimum 12.5 were the issue. Rather than just talk about the issue (a.k.a. Deflategate), engineers performed calculations and more. One company conducted experiments as well.

In its testing, HeadSmart Labs found that on average, footballs dropped 1.07 psi from temperature change in a 75°F room to a 50°F room. Exposing the football to water resulted in an additional 0.75 psi pressure drop. With the combined effects, the footballs’ pressure decreased by an average of 1.82 psi to a max of 1.95 psi.

Richard P. Binzel, professor of planetary science at MIT, calculated that a 5 to 10% drop in temperature could create a drop of 0.5 to 1.5 psi, in a football’s air pressure. Equally important, he noted that the accuracy of the meters used to measure the footballs is unknown.

The bottom line for this or any critical pressure measurement is that for accurate measurements, especially at lower pressures, temperature changes are among the operating environment aspects that should be taken into account and accurate meters need to be used.

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What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Dan DeFalco, Marketing Manager, All Sensors Corporation (ddefalco@allsensors.com)

Pressure Required for Pick and Place Equipment

Welcome to All Sensors “Put the Pressure on Us” blog. This blog will bring out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. This blog explores pressure required for pick and place equipment.

Pressure Required for Pick and Place Equipment

In the factory, pressure provides essential feedback for many operations. The measurement ensures both proper execution and accuracy of the process. One example is a pick and place station. In this case, a negative pressure (vacuum) lifts an object so it can be located on a work in process (WIP). If the object is not lifted for whatever reason (missing, broken, etc.), the sensor’s reading identifies an error so the WIP does not proceed to the next station. If the normal lifting pressure reduces over time due to leakage, wear or some other cause, the pressure reading can warn an operator to perform maintenance or initiate further machine diagnostics rather than have several defective operations occur.

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To create the vacuum, the pump requires energy and time to build to the right pneumatic level. It also takes time to empty the pick and place tool when it has to release the object. These factors all lead to a pump and operating point selection. Typical operating levels will vary based on the application and can range from low to high PSI pressures.

Do you have a pressure sensing question?
Let me know and I’ll address it in an upcoming blog.
-Dan DeFalco, Marketing Manager, All Sensors Corporation (ddefalco@allsensors.com)

Pressure Sensing in Healthcare

Welcome to All Sensors “Put the Pressure on Us” blog. This blog will bring out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. This blog explores pressure sensing in healthcare.

Pressure Sensing in Healthcare

When we’re young, it seems that the thermometer is the essential measurement to determine well versus sick. As we age, pressure becomes increasingly important. Initially, it determines a proper blood pressure level—with less than 120 over 80 (mm Hg) being the desired range.

Proper eye care involves glaucoma testing that uses pressure to determine the onset of this disease. Normal intraocular pressures average between 12-22 mm Hg.

A common tool for detecting the onset of respiratory problems is the spirometer or pneumotachograph. In this case, the reading is airflow rate calculated from a change in pressure drop (∆P) during inhaling and exhaling and can also be used for indirect measurement of lung volumes and capacities. The actual differential pressure measurement is quite low, typically requiring a sensor with as low as ±500 P (±3.75 mm Hg) range to obtain acceptable resolution.

These are the more common pressure measurements that separate a heathy from a sick person. Those with health problems may learn the difference between in vivo and ex vivo pressure measurements, and the use of pressure measurements in respirators, ventilators and more.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Dan DeFalco, Marketing Manager, All Sensors Corporation (ddefalco@allsensors.com)