Mensor manufacturers a wide variety of high accuracy pressure measurement and monitoring digital pressure gauges and transducers. Some of these pressure measuring and monitoring products have options for internal datalogging and data storage. Our stand alone transducers and the transducers used in our digital pressure gauges provide a digital signal that can be transmitted to computers or monitoring systems to record, save and analize presure data.
High accuracy pressure measurement and monitoring is essential in many critical applications where pressure has a direct effect on the product quality, quantity or process efficiency. Many times the pressure of a process will have a direct corolation to the value of the product being produced. Precicely controlling, measuring and monitoring the pressure is directly related to the bottomline for profit and quality.
For pressure measurement, monitoring and datalogging there are three product catagories that can fulfill requirements. For the purpose of this article they are identified as digital dial gauges, digital pressure indicators and pressure transducers, as seen below.
A CPG1500 digital dial gauge looks like a traditional dial gauge with integral process connection, a round case and a display on the front. However, in place of the mechanical inner workings, it has a pressure sensor and electronics that can digitally display the pressure reading. The display is backlit and includes various pressure related data collection and display functions, including data logging, min/max display, zero, tare, units selections, temperature readout, and more. Taking advantage of the onboard electronics, the gauge is also capable of remote data transmission via WIKA Wireless. An iOS or Android app is available to read and modify the settings of the gauge and act as an interface for data collection and transfer to a PC. When the gauge is to be used in a hazardous environment, an intrinsically safe version is available. The CPG1500 has an accuracy as low as 0.025% FS and ranges from10 inches of water up to 150,000 psi.
A CPG2500 Digital Pressure Indicator is a desk top or rack mount pressure indicator that can be configured with up to four transducers: one or two high accuracy internal transducers, one external transducer, plus an optional barometric reference, which can be used to monitor atmospheric pressure or emulate the pressure reading. The internal transducers are removable and interchangeable and can have custom ranges from 0-10 in H20 up to 42,000 psi with accuracies up to 0.008% IS-33. The interchangeability allows users to have reserve transducers that can be swapped out to achieve optimal accuracy, additionally an external Mensor transducer can be displayed on the CPG2500 using an RS-232 connection.
The color touch screen display can be configured to display up to three transducers. Differences or summations between sensors can also be displayed using the delta feature which is automatically accessible when more than one transducer is installed. Auxiliary display functions for min/max, pressure units, rate and pressure mode are selectable from the touch screen.
The CPG2500 can be calibrated using a laboratory standard on a regular basis and then used as a portable "transfer standard" to verify the readings of a field standard or portable pressure calibrator. It can also be utilized to monitor critical processes, or in a calibration bench application.
For calibration purposes the CPG1500 or the CPG2500 can be used. However, in calibration, a source of regulated pressure must be available as well as a way to read the output of the device being tested. If a mechanical gauge is being calibrated, a simple comparison of the readings would suffice. The CPG1500 is available in a kit that contains either a pneumatic (CPP30) or hydraulic hand pump (CPP700-H). However, there are many multi-function field pressure calibrators that have pressure sensing, pressure generation and signal measurement incorporated. These types of portable pressure calibrators are used for field calibration in hazardous and non-hazardous environments.
High accuracy transducers from Mensor come in a variety of accuracies and signal output choices. Although these do not have integral readouts they are used extensively for pressure measurement and monitoring and transmit pressure data to monitoring software for datalogging. Transducers have the advantage of delivering high accuracy pressure information at a lower cost relative to the digital pressure gauges above, plus they are in rugged stainless steel housings that can be connected directly to the process. Mensor Pressure Transducers communicate via a query and response or a continuous data stream via their RS-232 or RS-485 interface, alternatively the CPT6030 Analog Pressure Transducer output is 4-20 milliamps, which is very useful within data acquisition (DAQ) systems.
Datalogging is a function that is particularly useful when monitoring a process over a long period of time. Pressure data can be captured internally in the CPG1500 and transmitted through the WIKA Wireless interface. For Mensor digital pressure indicators and transmitters, datalogging is achieved through the various communication interfaces to a PC where data can be collected and analyzed.
The speed of transmission can be critical to capturing transient pressure spikes, slow leaks, or even pressure variations due to ambient conditions. Mensor measurement and monitoring equipment can be programmed to deliver pressure readings as quickly as 250 values per second (CPT6140), but the typical response time is 50 reading s per second. The CPG1500 has a selectable rate from 1/s, 3/s , 10/s or 50/s, and can internally store up to 1,000,000 points. Transmitters and digital pressure gauges can transmit their pressure upon a query from a computer 50 times per second but the query may come at any allowable interval and collection of data is limited only by the capacity of the computer memory. In most instruments a filter is used to dampen the effect of systematic noise on the pressure reading. In digital pressure gauges and indicators, the filter can be turned off or set at low, normal or high depending on the application. In the newest transmitters, the filter is a percentage of the previous reading averaged with the current reading - as long as the current reading is within the filter window of the previous reading. This filter window is set as a percentage of full span of the transducer’s range. If the current reading is outside of the window from the previous reading, the filter is unused and the current reading is displayed without manipulation. This scheme allows the user to tune the transducer’s response as they like. It also allows the transducer to respond to rapid pressure changes without having to change the filter.