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You are correct mag meters need to be in the pipe. Clamp-on transit time ultrasonic technology is used to read potable water flow (without particulate or bubbles; those are the domain of doppler technology). I doubt you will find 'cheap' sensors. Ultrasonic technology requires exciting...

Yes, RS-485 is technically 3 wire, the 3rd wire a signal common. It usually works OK on the bench with 1m cabling and no common mode between nodes, but 485 is not isolated like Ethernet is - NIC Ethernet cards used do transformer isolation with that little black 'magnetic' cube. RS-485 hub...

From the 344 manual: "If diagnostics detect an input sensor failure or a failure in the transmitter electronics, the transmitter drives its output to low or high depending on the position of the failure mode switch. If the sensor temperature is outside the range limits, the transmitter...

Page 751 (Section 5.7) in Liptak's Instrument Engineers' Handbook, volume 1, 4th Edition, is a one page comparison of Electronics Pressure Sensors, the sensing elements.

I'm lost. What's a pulse width modulated 4-20mA signal look like? A square wave at 4mA or 20mA? With pulse widths based on what kind of time frame?

That sounds like a mis-designed RS-485 network with 120ft stubs to a central point in a star topology. Google RS-485 hub and you'll find hardware solutions for RS-485 with long stub runs like this. Presumably whatever protocol you're going to use has some device addressing and can run on 485.

This 10 year old thread addresses ultrasonic differential measurements http://control.com/thread/1026222097 I've used what was Milltronics, is now Siemens, with two transducers connected to a single controller, the HydroRanger 200. The controller interface was updated a couple years ago...

Yes, but if you want reassurance B&B Electronics publishes the distance vs the baud rate chart for RS-485 communications, assuming 24AWG twisted pair cable (CAT 5 cable) and a balanced interface (RS-485). https://s17.postimg.org/cx0cgy0z3/cable_length_vs_data_rate_for_24_AWG_twisted_pair.jpg...

Google RS-232 current loop A current loop modem converts from RS-232 voltage to a current loop for the long haul and then back to RS-232 voltage at the other end.

If by 'digital' you mean a communication protocol like Profibus or Foundation Fieldbus, buy a replacement DP pressure transmitter that covers the same DP pressure range and is made of the same materials. Replace the pneumatic DP cell with the Fieldbus model and connect to your digital Fieldbus...

When the total resistance in the loop exceeds what the power supply voltage can drive current through, then the transmitter's output drives current up to the point the voltage supports, then faults in some mode. I saw this in action the transmitter repeatedly attempted to re-intialize (go...

You're right. As long as you have thermocouple or T/C compensating/extension wire on both sides of the connector, the error will be limited to whatever thermal gradient there is between the connections. Go for it.

One reason to use liquid fill is that liquid fill lubricates the movement's moving parts which reduces the effects of wear and extends the lifespan of the gauge. Is extended gauge life worth the price of quality liquid fill fluid?

See what Rosemount has to say about materials compatibility http://s22.postimg.org/q1kz43vlt/03_H2_S_compatability_Rosemount_Pressure.jpg

A HART or ISA100 wireless field transmitter talks to a 'gateway' which is wireless on one side, wired an Ethernet network on the other. The ISA100 gateway and the HART wireless gateways put the data from the field transmitters into Modbus slave/server Registers which can be read by a Modbus...

A rain gauge is an integrating function: the rain accumulates in the instrument as a 'level'. So your 'program' does not need to totalize, the rain gauge (inherently) does totalization by reporting level, not instantaneous rainfall. So RalphM's approach is correct - report the total as...

I have used two different clamp-on ultrasonic flow meters and neither had a minimum flow requirement. At zero flow, the meter would indicated zero flow without difficulty. In fact, I was told by the manufacturer in one case that best practice was to have a pair blocking valves used only to...

Assuming your transmitter is factory calibrated for a negative DP range, then using it over some other range than it was originally configured for is just a matter of changing the LRV/URV to the new range settings. But you should be aware that some smart transmitters are factory calibrated...

>However, there are control systems that have AI cards which are affected by the HART communication signal.< Interesting. What are the symptoms of 'affected by HART'? Noise on the signal? Jitter? Offset? HART noise component from aliased sampling?

Wow, great HART troubleshooting document. For those who don't download the document, they should know that it is probably the best HART troubleshooting document I've ever encountered. Because it assumes a HART handheld (375/475), it misses some issues with HART modems running software on...