Differential pressure between two rooms prevents dust, particulates, and pathogens from entering or exiting one room and going into the other. Depending on the relationship between rooms, one room will be under positive pressure when referenced against the other. This positive-negative pressure relationship between two spaces is the main idea behind clean rooms and isolation rooms. To ensure the differential pressure relationship is maintained, a measuring device must be used.
Room pressure monitors and room status monitors measure, display, and transmit the differential pressure reading between two rooms. In general, room pressure monitors only monitor differential pressure. On the other hand, room status monitors monitor differential pressure and additional parameters such as relative humidity, temperature, air change, or door status. They are both used in critical applications that require critical low differential pressure relationships. Continue reading “What are Room Pressure and Room Status Monitors?”
In this age of virtual meetings and online connections, to “Google” something has become synonymous with quickly looking up information. For some, bookshelves are more for decor than they are functional, and trends are leading to becoming more environmentally-friendly and saving paper. Print media is not necessarily “dead,” but it is becoming much less prevalent as we journey forward in this digital age.
When speaking on digital resources, we have to take this chance to talk about some of the benefits that our digital catalog can offer. Available on both desktop (via our website) and mobile (via the app), the digital catalog allows you instantaneous access to application guides, selection guides, and product specifications. Continue reading “A Dwyer Guide to the Digital Catalog”
High duct-static pressure creates problems during a building fire when fire dampers close. Closed fire dampers cause downstream duct sensors to detect a drop in pressure. The duct pressure sensors in turn send signals to crank the air handler even faster to get back up to normal operation. Because the fire dampers are closed, when the air handler ramps up, the duct pressure upstream of the fire dampers will increase to a point where a high static pressure switch will cut power to the VFD (variable frequency drive) and send a signal to the DDC (direct digital control). Switches in this application — by specification — are all manual reset and require two outputs: one for cutting power to the VFD and one for sending the signal to the DDC.
Stability is defined as a change (or lack of change) in accuracy over a period of time.
Drift is commonly used as a specification to illustrate the stability, or change in accuracy over a period of time, commonly shown as X%/year where X = a number; i.e. 0.25%/year. In this scenario, a device with a ±1% accuracy, would be expected to have an accuracy of ±1.25% (1%+0.25%) after a period of one year. Depending on the design, brand, and range of the sensing instrument, the stability can vary widely. Continue reading “What is Stability and Why is it Important?”
Steamfitters 449 is a union training center that represents nearly 2,700 union-trained steamfitters and are affiliated with the United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry of the United States and Canada.
According to the their website, members are highly trained craftsmen who fabricate, install, and service piping systems. Their craftsmen may be found on job sites involving single-family homes, garden and high-rise apartment buildings, supermarkets, food warehousing and processing facilities, power plants, chemical installations, factories, public buildings, and healthcare facilities.