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.
Traditionally, there have been three tactics to address this issue, each with its own problems. Continue reading “Solve High Duct-Static Cutout Problems with the Series 1831”
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.
Continue reading “Dwyer Instrumentation at Steamfitters 449 Training Center”
What is a Paint Booth?
Aerospace paint spray booths provide the ideal environment to paint aircrafts, such as fighter jets, commercial airplanes, and helicopters. The paint spray booths regulate humidity, temperature, airflow, and pressure for proper coating application and curing. The booths are categorized by three different designs, which are: air pressure, cabin, or airflow.
The air pressure design booth will either have a negative or positive pressure. The positive pressure means that the pressure inside the booth is greater than the air pressure outside of the cabin. The air pressure inside the booth is provided by an air make-up system and replaces the air being exhausted by the fan. Continue reading “Aerospace Application: Paint Spray Booth”
We recently met with Aaron, a customer working on a project in West Virginia who needed to replace pressure transmitters on water transfer pump skids.
The transmitters had been installed on the discharge line, and were outside exposed to the elements. The transmitters had plastic connectors which had a tendency to degrade over time due to the wind, rain, and sun, leading to premature failure. Without functioning pressure transmitters, the pump skids themselves would shut down and limit water transfer operations. Continue reading “Pressure Transmitters Used for Pump Skids”