negative pressure – Page 2 – All Sensors

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.

Suction Solutions

Designers often look to nature for ideas that can be implemented in new products. Octopus suction cups provide an interesting pressure example.

When the octopus’ sucker is sealed to a surface, contraction of its radial muscles thins the wall of the sucker which tends to increase the enclosed volume. However, the cohesiveness of water resists volume expansion and the pressure of the enclosed water decreases instead. With this mechanism, an octopus can create a pressure differential of 100-200 kPa (14.5-29 psi) at sea level and generate a significant amount of force.

Suction cups allow professional glazers to easily pick up and move large pieces of glass. One company offers a Vacuum Cup Octopus with Pump that can lift a maximum weight of 185 kg (407.9 lbs.) vertically with a 300-mm (11.8-in) diameter vacuum cup. One version includes a manual vacuum pump with a leak gauge to monitor the effectiveness of the suction.

Source: Vacuum Cup Octopus with Pump

Vacuum suction cups offer a versatile method of material handling. In fact, suction cups also allow robots to pick different smooth surfaced objects. The approach has been applied to the robotics field since the 1960s. One recent research effort focuses on suction cups that can be used on robots designed to perform tasks in unstructured and contaminated environments. Of course, monitoring the amount of vacuum (negative pressure) with an accurate and rugged microelectromechanical systems (MEMS) pressure sensor can provide an even greater amount of control to more sophisticated suction applications.

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The Pressure in Hospital Isolation Rooms

Infectious diseases and chronically ill patients require special air handling equipment in hospital isolation rooms. The isolation could dictate either positive or negative pressure in the room.

An isolation room at negative pressure has a lower pressure than that of adjacent areas. This keeps air from flowing out of the isolation room and into adjacent rooms or areas. In contrast, higher (positive) air pressure in the isolation room than in the adjacent corridor or anteroom prevents transmission from the outside environment to severely immunosuppressed patients.

Historically, the transmission of tuberculosis has been a concern for many years. The Centers for Disease Control and Prevention (CDC) published and updated “Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005” a little over a decade ago and identified the need for a negative pressure of at least 0 .001 inch of water to prevent spreading the disease. More recently, Avian Bird Flu H5N1, another highly contagious disease, has raised the need for isolation and negative pressure control. A pandemic disaster or chemical warfare could further increase the number of negative pressure isolation rooms/wards required in a community.

Monitoring the room to outside differential pressure can be performed with manual techniques such as visually observing the direction of airflow using smoke tubes or with a pressure gauge. Both of these approaches require the person monitoring the room pressure to be at the room. With today’s lower pressure and cost-effective MEMS sensors, remote monitoring can easily be implemented so an expert (or experts) responsible for ensuring the positive pressure does not have to physically close to the patient’s room – and receives the warning of a problem in real-time.

A pressure monitoring gauge is part of the isolation room equipment to monitor airflow. Source: http://biologicalcontrols.com/excbb.shtml

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Senior Marketing Specialist, All Sensors Corporation ([email protected])