The Pressure on a Ballerina’s Feet

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.

The Pressure on a Ballerina’s Feet

It looks so graceful when a professional ballerina executes classic ballet maneuvers and dances on the tips of her toes in pointe shoes (full relevé) and even hops across the floor. Getting to the graceful level takes a lot of training, practice and stress on the feet, ankles and more. The pressure on various portions of the foot have been the focus of several academic studies, some going back over 35 years or more. It turns out that simply walking in pointe shoes doubles the peak pressures acting on the foot compared to barefoot (860 kPa vs. 410 kPa).

Ballerina in pointe shoes

In one study, published in the Journal of Dance Medicine and Science, pressure data were collected with a high-speed, high-scan pressure platform sampling at 100 Hz. Female dancers in training, approximately 13.5 years old, were the test subjects and measurements were made as the dancers rose from demi-plié to demi pointe (intermediate pressure conditions). The researchers measured pressure and force data for barefoot, soft shoes, demi-pointe shoes and pointe shoes and pressure was recorded for specific areas of the underfoot for each shoe condition. In pointe shoes, the peak pressure is over 3 times the mean barefoot pressure.

Foot Pressure Chart

Another study of dancers in full pointe found that the average pressure on the toe box while on pointe is 220 psi or 1.5 MPa with the majority of the weight (pressure) concentrated on first toe. Even more dramatic results are a 60-kg (132-lb) ballerina landing on pointe from a height of one meter generates an impact force of approximately 4950 N or 700 psi. Its no wonder ballerinas feel they are under a lot of pressure.

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Water Cooler Pressures

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.

Water Cooler Pressures

A water dispenser that cools as well as heats water is a welcome addition in a home or office.  When the replaceable water storage unit is mounted at the bottom of the cabinet, it eliminates the hassle of lifting a heavy container. However, the bottom loader requires pumping water up rather than using gravity to dispense water. Simply transferring water from the bottom of the container to the dispensing valves, a distance of about 4 feet, would require a pump to generate at least 1.7 psi, so a 5-psi pump may be all that is required. Since the unit delivers chilled water, a refrigeration unit is part of the design. The high-pressure side of the compressor is 1.6 Mpa (232 psig) and the low-pressure side is .62 Mpa (90 psig). In contrast, these pressures are considerably lower than an air conditioning compressor such as a Samsung split system/ heat pump that is 3.1 Mpa (448 psig) and 1.6 Mpa (236 psig). It is interesting to note the significant differences in pressures required for a functioning water cooler.

Primo Water Corporation - Bottom Loading Water Cooler

A bottom loading water cooler
Image source: Primo Water Corporation

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Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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Refrigerator Water Filters and Pressure

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.

Refrigerator Water Filters and Pressure

Everything connected to a pressurized system needs to operate within the maximum pressure that system will experience to avoid leaks and other problems. For example, the EDR1RXD1 Everydrop water filter used on many different brands of refrigerators is a mechanical and chemical reduction filter with a flow rate of 0.5 gallons per hour (gph) and capacity to filter 200 gallons of water. As the contaminants that the filter removes build up, the filter should be changed every 6 months (or 200 gallons of water). While the filter can withstand 120 psi, to avoid problems, the manufacturer recommends installing a pressure reducing valve if the water supply is over 80 psi.

EDR1RXD1 Everydrop Water Filter

The manufacturer’s confidence in the filter’s ability to withstand 120 psi maximum pressure and then applying in a safety margin of 40 psi could be obtained from the material design parameters and simulation, but should ultimately be determine by qualification testing and then guaranteed in production by periodic quality control sampling. For the physical testing, an All Sensors SPA 401 series pressure sensor would be an excellent choice to make reliable and accurate measurements.

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Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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Pressure and Anti-Gravity Therapy

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.

Pressure and Anti-Gravity Therapy

After suffering a lower body injury such as a torn ACL, putting full weight on the injury can be quite painful. Conventional ways of reducing the weight include water-based techniques and suspension body harnesses. Both of these approaches have their shortcomings. To address the shortcomings, designers at AlterG® used patented Differential Air Pressure (DAP) technology developed by a NASA engineer to help astronauts exercise in lower gravity situations in their design of a treadmill.

The DAP system has a seal between the user’s lower body inside a chamber and the user’s upper body outside. With a chamber pressure, P2, higher than the ambient air pressure, P1, an upward vertical force (Fair) is created that is proportional to the product of the air pressure differential (ΔP=P2−P1) and the cross-sectional area of the user seal.

Anti-Gravity Treadmill Differential Air Pressure System

The patented differential air pressure system in an anti-gravity treadmill.
Patent US9642764B2.

A pressure sensor in the system allows feedback to the user. The incrementally adjustable air pressure system can reduce body weight by as much as 80%.

Anti-Gravity Treadmill

The user interface provides feedback to adjust for the user’s size and the desired amount of weight reduction.

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Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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