|Types of Sanitary Sensors|
|Below is a review of the most common types of sanitary sensors used for temperature, pressure, flow, and level control applications. OMEGA® provides a comprehensive line of 3-A sanitary sensors, and we will use examples from our various product lines for illustrative purposes. OMEGA also offers some unique products for wireless connectivity which can greatly simplify sensor installation and maintenance.
One of the simplest and least expensive 3-A temperature measurement devices is the dial thermometer. However, these sensors are limited to situations where manual monitoring is used and accuracy requirements are not too stringent.
The most accurate and most popular device for process temperature control is the RTD (resistance temperature detector, model PRS-3-100-A-H-0600-D1-NB9W shown left). An RTD that meets 3-A sanitary standards can be provided in the form of a probe for direct immersion (and faster response time) or can be enclosed in a thermowell for mechanical protection and ease of replacement. Direct immersion RTD sensors are provided with straight or stepped probe designs depending on response time and process flow conditions. The wetted surfaces are 316L stainless steel, and are highly polished to meet 3-A requirements. These sensors are also supplied with traditional connection heads, M12 connections, integral extension cables or wireless features for ease of installation.
The item shown to the left is a 3-A sanitary pressure transducer. This device is typically used in dairy, food processing, pharmaceutical, and biotech applications. Construction is all stainless steel with an electro-polished finish. This unit is designed for clean-in-place operation. This sensor utilizes thin-film technology which is known for reliability and accuracy. It is calibrated to NIST standards. The low response time of 5 msec ensures tight process control. The reading is delivered via a 1 to 5 Vdc output signal or a 4 to 20 mA current loop.
Sanitary turbine flowmeters, such as the FTB400A, are used in processing liquids and beverages. They are also found in applications requiring pasteurization and can be used for thicker materials such as ketchup and chocolate. Units are available in sizes ranging from ¼ to 3" in diameter. This type of sensor covers flow ranges from a fraction of a gallon per minute (GPM) up to hundreds of GPM. The design of the flowmeter and materials of construction are suitable for cleaning in place (CIP).
|Flow Transmitters and Switches
The Model FSW-9000 transmitter/switch monitors the flow velocity of the product based on the principle of thermal dispersion between heated and unheated RTDs immersed in the product. It generates an analog output signal corresponding to the flow rate and includes a set point feature which can signal a process controller or operator when a specified flow is achieved. If an actual flow measurement is not required, a simpler flow switch can be used to signal when the flow rate set point is reached.
In processes using a vat or other large container, the fill level can be accurately measured with non-contact sensors. These replace capacitance or float-type devices which require immersion in the product. The LVU1500, to the left, shows an ultrasonic level transmitter. This unit emits ultrasonic pulses which are reflected at the air/liquid interface to detect and measure the fill level. For situations where foam, dust, or vapors interfere with ultrasonic measurements, a radar-based level transmitter such as the LVRD500 may be used.
|Wireless Connectivity Options
A further refinement to sanitary sensor applications is through the use of wireless technology to transmit measurement data. Here OMEGA has a comprehensive range of products that simplify installation and maintenance, as well as add analytical and control software to improve process control and monitoring. The UWRTD-NB9W is an RTD-to-wireless unit that transmits measurements to a matching receiver that can handle up to 48 channels. Matching software logs data and provides process control signals.
|Anemometers | Automation | Accelerometers | Calibrators | Cartridge Heaters | Chart Recorders | Cryogenics | Custom Pressure Transducers | Data Loggers | Data Acquisition | Dial Thermometers | Fiber Optics | Flexible Heaters | Flowmeters | Glass Bulb Thermometers | Grippers | Heaters | Humidity Measurement | Immersion Heaters | Infrared Thermometers | Level Measurement | Load Cells |
Magnetic Flow Meters | Panel Meters | Pressure Gauges | Pressure Transducers | Rotameters | RTD | Remote Process Monitoring
| Sanitary Sensors | Signal Conditioners | Stepper Motors | Strain Gages | Strip Heaters | Temperature Controllers | Temperature Labels | Temperature Measurement | Temperature Sensor Manufacturing | Temperature Transmitters | Thermal Imagers | Thermistors | Thermocouple |
Thermocouple Wire | Thermowell | Ultrasonic Flow Meters | Wireless Sensors