• How to protect pressure transmitters from medium pulsation accompanying hydraulic shocks?
   
  You can use the TTR pressure snubber, a special accessory, to protect your pressure transmitters from medium pulsation accompanying hydraulic shocks. The snubber is a multi-chamber device with special washers and misaligned holes that extinguish the shocks. Limitations of TTR: medium temperature up to 95 °C, medium pressure up to 70 MPa, no strong contaminants and suspensions in the medium. Within those limitations, our lab tests proved the guaranteed hydraulic shock protection of up to 20 ms. We recommend mounting the TTR snubber on the valve unit; it is easier and more convenient. Our rich experience tells that an assembly of a transmitter, a snubber and a valve block is an optimal solution from the point of view of ergonomics: snubber protects transmitters and extends its service life and valve block makes maintenance and replacement quick.

 

• We need to control the level of highly concentrated sulfuric acid at a power plant, which transmitter do you recommend?
   
  To pick the level transmitter for your situation, you need to know the exact data on temperature and concentration of sulfuric acid. Typical choice are transmitters with PVDF housing and ceramic diaphragm. For example, if you need to control the level of sulfuric acid (H2SO4) with the concentration of up to 10% and temperature at 50 °C max, you need a PVDF transmitter with a ceramic diaphragm, FKM seals and TPR jacketed cable. We do make such transmitters, e.g., LMK 858 hydrostatic level transmitter. Strong acids and alkalis require high-purity ceramic diaphragm (99.9%).

 

• How do we measure the level of oily water in a tank? What would you recommend?
   
  Much depends on the characteristics of the mixture/solution when you need to measure the level of oily water in a tank. The thing is, hydrostatic level transmitter work correctly only with the constant density media. If oil is just a thin film on the surface of the water, the transmitter will likely report levels correctly.

 

• Is it necessary to install the IS barrier when using intrinsically safe versions of pressure transmitters?
   
  Yes, it is. Moreover, the barrier should comply with the following conditions: Ui> = U0, Ii> = I0, Pi> = P0, Li + Lc <L0, Ci + Cc <= C0, where
  Ui, Ii, Pi, Li, Ci - maximum values of parameters for IS equipment (transmitter),
  U0, I0, P0 - maximum values of parameters for accompanying equipment (barrier),
  L0 - maximum permissible inductance in the external intrinsically safe circuit,
  C0 - maximum permissible capacitance in the external intrinsically safe circuit.
  You will find the Ui, Ii, Pi, Li and Ci values for transmitters in the annex to the Ex conformity certificate.

 

• What is the best way to protect the cable of the level transmitter?
   
  Some models of BD Sensors RUS submersible pressure transmitters can come with a corrugated metal jacket protecting the cable from ice (on the tank's surface) and solid inclusions. This jacket is an option.

 

• What is the difference between a sealed gauge pressure sensor and a regular gauge pressure sensor?
   
  As a rule, sealed sensors measure in the range greater than 60-70 bar. There, atmospheric pressure changes produce no noteworthy effect, so the reverse of the chip is kept sealed from the atmosphere, which also extends service life of the transmitter because the crystal's reverse receives no condensate. You can say that such sensors are absolute pressure sensors, but instead of vacuum they have atmospheric pressure on the reverse. Such sensors are used in transmitters DMP 333, HMP 331, DS 200, XACT i, the range of which is 70 bar and above.

 

• What is the pulse tube for?
   
  Pulse tube drains pressure. In addition, pulse tubes is a low cost solution when the medium temperature is high. Each meter of the pulse tube lowers the medium temperature by about 80 degrees. Typical pulse tubes materials are steel or copper. The end of the pulse tube that connects to the pressure source is prepared for welding, its other end, which connects to the transmitter, has a cap nut threaded to meet the transmitter's thread.
   

 

• We need a transmitter for aggressive media (highly mineralized saline water).
   
  If you need a submersible level transmitter to measure level, e.g., in a well, the best choice is  LMK 358, a transmitter housed in stainless steel and bearing a ceramic diaphragm. If the medium is too aggressive for steel (like seawater), you can pick the LMK 458 special version submersible transmitter that comes in the CuNiFe corrosion resistant housing. A set-in alternative is LMK 351 with a ceramic diaphragm, which is more resistant to aggressive media. LMK 351 can also have the housing made of PVC or PVDF.

 

 

• What if we need to register pressure in a non-standard range?
   
  BD Sensors RUS can manufacture pressure and level transmitters tailored to your needs: non-standard range, non-standard pressure ports and electrical connections, non-standard output signals etc. You simply need to specify the range needed in your application   and our specialists will check if we can make such a transmitter and if that range is compatible with other parameters of the device you mention in the application.

 

 

• Which HART modems and communicators connect to your transmitters?
   
  Our transmitters are compatible with HART-modems and communicators that are made in strict compliance with the HART specifications. We recommend using modems and communicators by BD Sensors: MH-02 or HI 311 (HI 321). You can find the list of the most common HART commands in Appendix D, pages 38-39, to the Operation Manual.
   

 

• Our setup implies heavy electromagnetic interference. How do we ensure the transmitter operates correctly and reliably?
   
  First off, we recommend keeping transmitter's cables (signal and power) away form high-current lines and sources of strong electromagnetic interference (large current relay-switches, welding machines, starters, etc). If that is not possible, you need shielded cables for your transmitter.

 

 

• What is a multirange pressure transmitter and when do you need one?
   
  This is a pressure transmitter the range of which can be changed as needed by the user. You need one when you do not know the range of pressure to be measured initially or when that range can change over time. After readjustment to a new range, the entire scale of the transmitter is used. In some cases, range adjustment leads to changes in accuracy (see the corresponding formula in the Manual).
   

 

• How do you choose the diaphragm seal correctly? What situation allow picking a transmitter without such seal?
   
  You need to know chemical composition of the substance subject to pressure control, as well as its concentration and temperature. These data allow choosing the material for diaphragm seal and washer, which are wetted. Do contact us if in doubt, our specialists will help you make the correct choice. if the medium temperatures are low (up to 85 degrees) and it is non-aggressive, you can pick a significantly cheaper transmitters without a diaphragm seal. On the other hand, diaphragm seal is a mandatory element of the transmitter if you use it in food, chemicals, pharmaceuticals production due to strict sanitary standards observed there. For food factories, we manufacture pressure transmitters filled with edible oil behind the seal, which makes it an even safer choice.

 

 

• What is the maximum overload capacity of your transmitters? Do they continue operating when the range is above nominal but below maximum permissible?
   
  Please see the Operation Manual for the max permissible  overpressure, i.e. pressure that the transmitter can bear without breaking down. In most cases, it is 3 ... 7 times higher than the upper range limit. If the pressure in the system does not exceed the max permissible overpressure and the number of loading cycles stays within the transmitter's design capacity (typically 100 million cycles), then, when the system pressure normalizes to within the nominal range, the transmitter regains its operational capabilities without losing in accuracy.

 

 

• Which software do we need to set the level scale of HART-enabled transmitters and how does that affect their accuracy?
   
  Any HART software developed in strict compliance with the HART specifications. To be on the safe side, choose software by BD Sensors RUS: config and CONF401. You can calculate the accuracy of the transmitter with adjusted scale using the formula given in the Operation Manual. Please note that accuracy remains the same when most nominal ranges receive insignificant adjustments (max 5 times depending on model and range) to the upper range limit.

 

 

• How do we become your dealer or representative?
   
  First off, send us an application. We are interested in finding dealers among successful companies supplying instrumentation and automation solution to oil and gas companies, chemical plants, machine building factories, shipyards, providers of energy, housing and public utilities, car manufacturers, pharmaceutical facilities, food and food processing industry. We are also looking for partners specializing in integrated automation solutions, equipment design and complete supplies.

 

• How to meter flow in a pipeline with the help of a pressure transmitter?
   
  You need differential pressure transmitters capable of calculating quadratic function, such as DMD 331-A-S. The following formula describes the dependence of flow rate on pressure drop as applied to a Venturi tube:
  formula
  ,
  where S1 and S2 are cross-sections of pipe and taper in m2, p = p1-p2 is pressure drop, Pa, ρ is medium density in kg/m3, A is the experimentally determined coefficient describing loss of pressure to friction. As a rule, its values range from 0.95 to 0.99.
   
  You need to set up the transmitter correctly to use it as a flow meter.

- Set the quadratic conversion function

- Set the appropriate upper range limit

- Set the flow to match that upper range limit

- Switch the transmitter to the metering mode

Setting up takes a special magnetic pencil and/or a HART modem. Also, you can switch on the momentary flow rate reporting in your preferred UoM.

 

 

 

• What are the advantages a digital interface pressure transmitter has over an analog interface pressure transmitter?
   
• The majority of current devices connecting to transmitters are digital. Therefore, when using a digital interface, you suffer no accuracy loss due to digital-to-analog and analog-to-digital conversion of the signal.
• Also, digital signal travels intact farther (up to 1 kilometer).
• BD Sensors RUS transmitters send out two parameters  through the RS 485 interface: pressure and temperature.
• Digital signal pressure transmitter connects to a computer through USB (using an inexpensive RS485-USB adapter),
• Digital interface allows joining transmitters into a network.
• Compared to analog interfaces, digital interface serving differential or FM signal (like RS485) boasts better noise immunity.

 

 

• What is the maximum length of cable of a submersible level transmitter?
   
  The standard version of LMP 308i hydrostatic level transmitter allows measuring level of liquid up to 350 m. If you face a range exceeding 350 mWC, BD Sensors RUS will design and manufacture a level transmitter tailored to your needs. Please specify maximum and minimum levels of the liquid column in your application. Our specialists will check if we can make such a transmitter and if that range is compatible with other parameters of the device you mention in the application.
   
  Designing liquid level monitoring systems, you also need to remember about the sufficient length of the level transmitter's cable. Level transmitters feature a special (hydrometric) cable that delivers atmospheric pressure to the sensor. Once the cable reaches the atmosphere, it can be brought into the termination box; the signal can be carried by a regular cable up to the connection point.

 

 

• What is a hydrostatic level transmitter? When do we need one?
   
  Hydrostatic level transmitters measure pressure of liquids in vessels or natural reservoirs and convert it to level. The pressure measured is hydrostatic; it is directly dependent on the liquid's level and density, but the reservoir shape does not affect it.
  
  The hydrostatic pressure formula is P = ρgh, where ρ is the liquid's density, g is the gravity acceleration, h is the height of the liquid column.
  
  Hydrostatic measurement works great with liquids of constant density. Hydrostatic level transmitters are mainly used to control level in wells, collectors, natural or artificial reservoirs, vessels, fuel tanks and other containers. From the point of view of deployment, level transmitters can be submersible and set-in.

 

 

• What is special about pressure transmitters designed for food industry (sanitary versions)?
   
  Pressure ports of the food-grade pressure transmitters feature a flush diaphragm. This design allows using transmitters to measure pressure of viscous, dense and inhomogeneous media. The diaphragm seal in such transmitters is filled with special edible oil. The possible pressure port versions are DIN 11851 (hygienic union), Clamp, Tri-clamp, VARIVENT. The housing of some food-grade pressure transmitters makes their cleaning simple and convenient.

 

 

• What is the accuracy (accuracy class) of a transmitter? What defines it and what does it depend on?
   
  Generally speaking, the transmitter's accuracy describes the difference between the real value of a parameter measured and the value registered and reported by the transmitter. Accuracy is the sum of basic reduced error and the additional error.
  
  The basic reduced error includes the measurement error, inaccuracy resulting from nonlinearity, hysteresis, calibration errors, temporary instability inaccuracy as a result of aging of the sensitive element. The additional error comes from changes in media temperature, supply voltage and load resistance.
  
  The UoM of pressure transmitters are percents of the upper range limit (url) or span (pressure range).
   

 

• What is the transmitter's long term stability and how is it related to the calibration period?
   
  Long term stability is the transmitter's ability to retain its parameters and characteristics (such as accuracy) over time. The greater the long term stability, the longer the calibration period.

 

 

• What is the Safety Integrity Level (SIL)?
   
  IEC 61508 standard describes four Safety Integrity Levels (SIL); they are applied depending on the severity of the consequences that may occur if the system is not functioning properly. Thus, SIL determine the acceptable risk for the system. They reflect the likelihood of the system discharging its safety-related functions properly.

 

 

• What is the transmitters' designed service life?
   
  Lifetime of pressure transmitters  depends on the properties of medium and operating conditions. The average service life of transmitters made by BD Sensors RUS is no less than 12 years.

 

• What is the outdoor housing of a pressure transmitter?
   
  Outdoor housing has electrical connections hidden inside; you need a cable to connect to a transmitter in an outdoor housing. Such a design allows using the transmitter outdoors, as the name implies, with its electricals protected from mechanical damage and atmosphere.
  
  Most compact transmitters made by BD Sensors RUS can have such housing as an option and it is the default option for Ex versions of transmitters. Pressure transmitters with outdoor housing can have an integrated display.

 

 

• How do I know a company selling your transmitters is an official dealer of BD Sensors RUS?
   
  BD Sensors RUS issues a certificate to its official dealers, which is valid for 1 year. This certificate confirms that the company it was issued to enjoys dealer discounts throughout the term of its validity, and that an employee of that company has been trained by BD Sensors RUS and can give qualified advice pertaining to pressure and level transmitters made by BD Sensors RUS.