Contact-type level instrumentation rebounds

FOR THE past few years, Control’s annual level-instrumentation roundup has observed many non-contact radar and ultrasonic-level instruments, and a scarcity of new versions of traditional instruments. Market researchers were probably gloating (or surprised!) to note that one of their predictions had actually come true: that radar and ultrasonic sensors would be the fastest-growing segments.

For instance, Venture Development Corp. (VDC) recently reported in executive editor Jim Montague’s “Rising Levels of Process Level Measurement Devices,” Control, Nov.’05, that, “The largest relative gains in continuous measurement technologies are expected for microwave/radar contact/guided (10.6%) and non-contact sensors (8.4%).”

Though true before, this trend isn’t reflected in the products in this year’s roundup. Now, there are more non-non-contact sensors in our roundup than ultrasonic and radar sensors. And, despite contributing author David Spitzer’s glowing coverage of laser sensors in “Zap! How Do It Know?” Control, Feb. ’06, we see no new laser-based sensors in this roundup.

In fact, because not all of the non-contact sensors listed below are actually new—some are enhancements to existing products—this year’s roundup may indicate a return to relative normalcy in the level industry.

This year’s roundup shows more agreement with VDC’s forecast that, “While there likely will be a barely perceptible shift from mechanical to electronic sensing technologies in continuous measurement, shipments of mechanical point measuring/sensing devices will outstrip electronic types.” VDC’s global study, “Worldwide Process Level Measurement and Inventory Tank Gauging Markets, October 2005,” also anticipates above average growth for float switch (6.7%), vibration (6.4%), and paddlewheel (6.1%) measurement devices.” We’re again seeing some of the devices below for the first time in a coon’s age.

You’ll see a mixed collection of all sorts of level sensors in the following roundup, including radar, ultrasonic, float, magnetostrictive, weight-based, vibrating fork, thermal and pneumatic devices. That’s the way it should be. Instead of rolling over and playing dead in the face of increasing non-contact sensor sales, other vendors see a growing economy, have more confidence in the market, and are starting to roll out new, contact-type sensors. Hooray!

Product Roundup:
Level Instrumentation

Level Transmitter Sounds Good
Type 8175 ultrasonic level transmitter has 0.25% FS accuracy over a 1.0 to 32.0-ft range, with resolution of 1/8 in. The non-contact transmitter is suitable for continuous level control, on/off level measurements of fluids/solids, flow measurements in open channels, and volume and distance measurements. It includes an ultrasonic sensor, transducer and eight-digit, multi-language display protected by a NEMA 4 enclosure. More info at controlglobal.com. Burkert; 800/325-1405; www.burkert-usa.com

Unchain My Sensor
RP resistive-chain level measurement sensors are shock resistant, have an anti-stick float, and are suitable for bulk-liquid product applications. The sensors operate with a float that travels up and down a vertical stem. A permanent magnet inside the float acts on a series of closely set reed switches and resistors inside the stem. The sensor converts the resistance value into voltage, providing current signals proportional to the level of the liquid. Scientific Technologies; 888/349-7098; www.stiapg.com.

Magnetorestrictive Sensor
BW Controls 7230 explosion-proof sensor measures total level, interface level, and up to five temperatures. The temperature sensors are distributed evenly over the active length of a stainless steel tube. It has a Modbus RTU digital output and optional analog converter, and is suitable for applications where the dielectric constant or density of the liquid is unstable. Ametek Automation & Process Technologies; 800/635.0289; www.ametekapt.com

Pushbutton, Plug-in Programming
SmartPress Model LP-D pressure/liquid level transmitters come with a 10-year warranty. The two-wire, loop powered transmitters provide pushbutton programming, and can be supplied pre-calibrated by the factory at no added cost. An optional plug-in programming/display module, which can be moved from unit to unit, provides full setup and display capability. More info at controlglobal.com. Princo Instruments; 800/221-9237; www.princolevelcontrols.com

TIP, Remote Point-level Control
RF Series point-level indicator has no moving parts, and isn’t affected by material coating. One-step calibration eliminates many steps formerly needed to calibrate and test level controls. “Test-In-Place” allows users to test level controls without removing the cover, or from a remote location. This is especially important for hazardous applications or where fugitive emission releases must be prevented. Bindicator; 800/778-9242; www.bindicator.com