Several applications require manual reset switches, which are switches that need to be physically reset by an individual for a process to continue or restart. A manual reset is often needed when an area has to be inspected prior to equipment restart. This can help to ensure the safety/inspection of both equipment and other individuals in the area.
Some switches have a mechanical manual reset (such as the Dwyer Series 1900, 1831, and 1800). However, there may be a need to have a manual reset for applications beyond what these switches are designed for. If a pump is allowed to run with a clogged filter, for example, this may severely damage the pump.Continue reading “How to Program a Switch for Manual Reset”
There are two common ways to measure air velocity: by using pressure-based instrumentation or by using temperature-based instrumentation. Before we discuss the different technologies available for measuring velocity pressure, it is important to understand the basics of air velocity.
There are a wide variety of technologies that can be used for fluid flow measurement, such as differential pressure, paddlewheel, electromagnetic, and ultrasonic. Furthermore, each technology has multiple installation configurations. It is important to understand the nuances of different technologies and installations in order to pick the right flowmeter for your application.
When purchasing a flowmeter for an HVAC application, such as boiler feed water monitoring or chilled/condenser water monitoring, we found that our customers value the ability to hot-tap (or pressure tap) a pipe to install an insertion flowmeter. This is done by installing an isolation valve in a pipe, allowing an insertion flowmeter to be placed into and removed from a live system without having to drain it. Draining a system is time consuming, costly, and generally not a good option for HVAC systems in buildings because it requires the entire system to be shut down. Permanently installing a hot-tap valve followed by an insertion flowmeter (with hot-tap capability) is an ideal alternative to a costly inline meter.
Proper selection and use of relative humidity (RH) sensors are important factors in designing and building a reliable, economical HVAC system. Over the years humidity control has been getting even greater attention because of its positive impact on indoor air quality (IAQ).
The importance of humidity measurement and control can mean different things depending on the application. To the museum curator, it means preserving valuable artwork and artifacts. To the hospital facilities engineer, it means a comfortable environment for the patients, as well as maintaining accurate moisture control to prevent the spread of bacteria and infection. And to the building maintenance professional, it means a reliable building automation system that reduces energy costs while increasing the comfort of its occupants.Continue reading “What to Consider When Selecting a Humidity Transmitter”