California’s Proposition 65 (Prop 65), officially known as The Safe Drinking Water and Toxic Enforcement Act, is a California law that requires manufacturers to place a warning label on any product that the State of California has found to cause cancer, birth defects, or other reproductive harm. This law was initially enacted in 1986 to assist Californians with making informed decisions on the products they were purchasing which might impact their drinking water. Since then the law has been extended to include all routes of contact such as eating, drinking, touching, and inhaling. Prop 65 helps consumers stay informed with what chemicals they are in contact with. The basic premise required products to have warning labels; however, products can vary in their use, consumption and how they come in contact with people. For example, a Prop 65 warning may be listed on something simple like a food storage container in restaurant or a more complex product such as a pressure transmitter used to measure water pressure in a municipal drinking system.
Dwyer Instruments, Inc. offers many flow measuring products including our very popular variable area flowmeters, often called rotameters. Dwyer manufactures variable area flowmeters in polycarbonate, the Series RM and LFM; in acrylic, the Series VF; and in glass, the Series VA and DR.
Variable area flowmeters have scales calibrated for specific media at specific conditions. Most commonly, the flowmeters are calibrated for air for gas use, and water for liquid use, at standard atmospheric conditions of 70 degrees Fahrenheit and 14.7 PSIA, which is 0 PSIG. When using the flowmeter in conditions other than these standards, the flow reading will not be accurate and corrections will need to be made.
Gases can have large differences in density based on pressure and temperature. The observed reading of the flowmeter is the actual flow rate. The flow rate corrected for pressure and temperature is the standard flow rate. Often for air use the pressure in the flowmeter is not atmospheric and a correction must be made to get the standard flow rate.
For correcting the flow rate to standard use the equation shown, where actual pressure P1, actual temperature T1, and actual flow rate Q1 are used.
When using the flowmeter for gas other than air, the specific gravity must be corrected for.
For this correction use the equation shown, where actual flow rate is Q1 and gas used in the flowmeter specific gravity is SG.
If manual corrections are not desired, Dwyer offers scales calibrated for other specific media; for example, nitrogen versus air. Dwyer can even create custom scales calibrated specifically for your application media, operating pressure, and temperature. Please contact our technical sales department for already existing scales or to have your own custom scale created.
Have you ever wondered why there are a multitude of sensor output signals that can be configured on pressure, temperature, humidity, or gas sensing instrumentation used in process or HVAC applications? Most of these offerings were originally setup to allow sensor manufacturers to better align with the inputs offered by manufacturers of programmable logic controllers (PLCs) and direct digital controllers (DDCs), which are used for controlling processes for both automation and HVAC control.
I’d like to focus on two of the most commonly used output signals and zero in on the advantages and/ or disadvantages these output signals offer. Two of the most commonly used output signals include analog current, typically 4 to 20mA, and analog voltage, typically 0-10V. Continue reading “Understanding Sensor Output Signals”
Question: Can the standard Series 160 Pitot Tubes be used to sense liquid flow as well as gas flow? Continue reading “Ask the Expert – Sensing Liquid Flow with DS Flow Sensor”