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The K-114 interface converter replaces the existing K-104 converter, although this model will also remain compatible with all KELLER digital products in the future. This means that there is no need to replace existing converters.

The K-114 interface converter is used primarily in conjunction with KELLER products that have an RS485 interface, such as Series DCX, Leo Record, Series 3X / 4X or GSM-2.

The RS485 half-duplex signal from connected devices is converted into a USB signal by the interface converter, which can therefore be connected to any desired computer with a USB port.

For more information on the K-114 converter and its capabilities, click here.

Keller digital pressure gauges (a.k.a. digital manometers) are a cost-effective solution in any pressure monitoring scenario where a local display is required. Features include min/max display, selectable units, 5 kHz scan rate for transient capture and data recording. These devices can also be built for service in oxygen applications.

These instruments are commonly used as fuel pressure gauges, hydraulic test pressure gauges, water pressure gauges and oil pressure gauges. Almost any installation previously utilizing mechanical or hydraulic pressure gauges can benefit from an upgrade to Keller technology.

Manufactured 100% in-house, Keller products incorporate the latest in microprocessor-based electronics and rugged, weather-proof enclosures, resulting in outstanding performance over a wide temperature range at reasonable cost.

For more information on the best Keller pressure gauge for your application, contact Keller today!

Keller America is pleased to announce that we will begin operations in our new state of the art facility on Monday, October 29, 2012.  The new facility incorporates the newest innovations in Keller manufacturing technology to allow us to provide the best possible quality and service to our customers.  To facilitate this transition, normal operations at our old location will be suspended on Thursday, October 24^th and Friday, October 25^th.  A customer service representative will still be available during normal business hours on these days to answer your calls.  Normal operations at the new facility will resume on Monday, October 29^nd.

Please be advised that any orders taken for stock products and Keller America transmitters taken after October 19^th may be affected during this transition.  Orders for stock products will be shipped as possible up until Wednesday, October 24^th.  Shipments for stock products will resume on Monday, October 29^nd.  Please allow 5-7 business days for shipment of Keller America level and pressure transmitters taken after October 19^th.  After approximately one week in the new facility, normal three business day shipment of Keller America level and pressure transmitters should resume.

Miniaturization in pressure measurement technology

Keller’s OEM transmitters are systems that can be described as “embedded” in the best sense of the word – and in two different ways. First the sensor and the downstream electronics are embedded in the same housing. And second, the transmitter capsules themselves are ideally suited for embedding in application-specific systems. Depending on requirements, the output signal is standardized and temperature-compensated (ratiometric or digital).

Thanks to Chip-in-Oil (CiO) technology developed at Keller, the trend toward sensor miniaturization is now a reality. This development can offer impressive advantages: an extremely compact structural design, high resistance to electrical noise fields, and high vibration resistance thanks to low mass and short conduction paths.

To put it clearly, CiO technology means that an ASIC is fitted directly next to the pressure sensor – in the same housing – to provide users with a whole range of beneficial functions. However, this does not make the pressure measurement capsule any larger;  Its external dimensions remain the same. This transmitter concept is available in housings 4L…9L, starting from a diameter of 11mm.

Sintered-in pressure-resistant glass lead-throughs feed the transmitter signals outward. The internal Wiring uses short, lightweight bonding wires – with the total exclusion of air in oil. First, this approach eliminates the need to connect filigree signal processing boards with multi-wire cabling in the rest of the installation process for the pressure transducer. And second, there is no need to protect the downstream electronics against moisture and condensation.

Together with the high-grade steel housing, the glass lead –throughs act as feed through capacitors, forming a Faraday cage. This makes the CiO technology extremely resilient to electrical fields. Even field strengths of 250V/m at frequencies of up to 4GHz are unable to influence the measurement signal. The digital interface must be protected by the equipment manufacturer itself.

The ASIC is designed as a microcontroller with the corresponding peripherals, so the sensor signals can be registered with high resolution and dynamism. In addition to the process pressure as such, the temperature of the pressure sensor is measured and is used for mathematical compensation when the signal is processed.

OEM transmitters supply two signals: a ratiometric analog voltage output and a digital inter-integrated circuit interface (12C).

Ratiometric output signal

The secret of the ratiometric format to the output signal is that it actually has no format at all, because it depends on the voltage supplied. This is an inestimable advantage for applications in integrated systems. If the analog-to-digital converter downstream of the transmitter is operated with the same supply voltage, the digital measured value will always be correct. This is because the height if the digitization steps depend on the voltage supply, but the number of steps does not – and their number is the critical factor. Using ratiometric signals substantially reduces the outlay on passing signals from the pressure transmitter to the A/D converter in the downstream electronics, and calibration steps are unnecessary; in the specific case of connection to a microcontroller with an integrated A/D converter, this outlay equals zero. Nevertheless, an interval is specified for the output signal, i.e. 0.5…4.5V for s supply voltage of 5.0V. With a stable and precise supply voltage, this interval can also be used directly as the “standard signal.” The sampling rate of 2 kHz offers amazingly good dynamic scope for a product based on the AD/DA principal. Moreover, the embedded electronics in CiO technology provide constant protection against overvoltage and polarity reversal on all lines up to ±33 VDC.

Embedded interface I2C

OEM transmitters that are the same size as pressure measurement capsules are never connected directly to field bus systems. Instead, the respective coupling modules have corresponding input interfaces, e.g. for the inter-integrated circuit or I2C interface. For years, this has been the serial standard to cope with short distances in embedded systems. The I2C master needs two lines for the serial data and the pulse (clock) for synchronous sampling. Consequently, no timing requirements are specified for the master – which, in fact, determines the timing. Each OEM transmitter has its own address, which is addressed by the I2C master. In the existing configuration, one master could manage 128 different addresses. The pressure and temperature values are registered by means of a request from the master, and are then available at the transmitters (slaves) after less than 10ms, so that they can be clocked out according to a specified protocol. The values are temperature compensated and standardized, and they only need to be scaled from the 15-bit integer to a pressure and/or temperature with units.

Mobile Application

Unlike the CiO version with the ratiometric output, CiO versions with I2C output can operate with a voltage supply of only 1.8…3.6 VDC, so they are excellently prepared for mobile battery-powered applications. In this case, however, features also include the short conversion time of less than 10ms (during which a mere 1.5mA is drawn) and the excellently optimized Sleep mode: unless they are polled, the transmitters remain in this mode, which is typically specified as 0.1µA. If the master allows suitable fast communication, 100 samples per second can be therefore be attained.

OEM transmitters for Everyone

Typical key data vary according to the format of the output signal – ratiometric or digital. With an analog output, the transmitter can be used at temperatures between -40°C and +150°C, whereas the I2C output is subject to an upper limit of 80°C. The pressure range for the analog version extends from 2 bar to 1000 bar; for the digital version, the range is from 2bar to 200 bar. For a greater dynamic scope with increased power consumption up to a maximum of 8mA, the analog version should be chosen. For low voltage and low power applications, the digital version (which also provides temperature information) is recommended.

Summary

Keller’s C-series OEM transmitters herald a new chapter in the history of high-integration pressure measurement technology. The Chip-in-Oil concept moves signal processing directly into the protective oil-filled pressure measurement capsule housing, made of stainless steel. Linearization, temperature compensation and parameterization are handles here. For integration into higher-level systems or battery-powered devices, versions are available with ratiometric voltage output or with a serial-digital I2C interface. Various structural designs can be supplied depending on the specific application.

Chris Lilly discusses Keller level and pressure transmitters with Angela Godwin with WaterWorld. We have had a great deal of success with the AWWA tradeshow and we look forward to next year’s show. Special thanks to WaterWorld and Angela Godwin for the footage!

Keller America is pleased to announce that construction has begun on their new facility. Scheduled for completion in early to mid autumn, this building will house the newest innovations in Keller manufacturing technology to better serve our continually growing customer base. We would like to thank each of you for your support of Keller products, and look forward to the new opportunities that this facility will provide.

Along with the increased production capabilities, Keller is also proud that this facility is on the leading edge of environmentally friendly construction, utilizing geothermal climate controls and construction materials chosen to provide outstanding durability and minimize environmental impact.

In addition, all irrigation will be provided by captured rainwater. Since Keller instruments are often used for applications like this, Keller will install several of their own DCX, GSM, and liquid level instruments for level monitoring and control. These systems will also serve as a training opportunities for customers and employees, alike.

Mark Miller, General Manager for Keller America, spoke with Angela Godwin of WaterWorld  magazine at  WEFTEC 2011.. Mark offered some insight into the Keller organization and on several products that have made Keller a world leader in level and pressure measurement. For more information on which Keller product is appropriate for your application, contact Keller America at 877-253-5537 or email sales@kelleramerica.com.

Keller now offers the Digilevel, an SDI-12 level transmitter.  This new instrument employs Keller’s proven sensor technology coupled with an SDI-12 serial-digital interface to create a more versatile and valuable tool for environmental level monitoring applications. SDI-12 is a standard communications protocol used to interface microprocessor-based sensors with data recorders for environmental data acquisition.

This convertible instrument may be used for either submersible level or bubbler pressure measurement with user-selectable pressure connection caps. The conical cap is designed to promote automatic cleaning of the sensing diaphragm, helpful where the submersible level transmitter is deployed in high-silt conditions. The alternate bubbler transmitter cap provides a 1/8”NPT female pipe thread for connection to the bubbler apparatus.

The Digilevel is compatible with all SDI-12 v1.3 commands. In addition, it is capable of operating in several emulate modes for popular SDI-12 level/pressure transmitters including manufacturer-specific extended commands. A graphical user interface and Dongle are available options for those who may be unfamiliar with SDI-12 commands.

For more information about the Digilevel, you can view the datasheet here. If you have any questions, please call 877-253-5537 or email sales@kelleramerica.com today.