Interview Questions.

Question 1. How Do Ultrasonic Level Sensors Work?

Answer :

An ultrasonic sound pulse is pulsed 4 instances in keeping with 2nd from the bottom of the transducer. The pulse travels thru air, displays against the technique medium beneath and returns to the transducer. The sensor measures the heartbeat time of flight between sound technology and receipt, and translated this into distance or liquid stage peak in the vessel.

Question 2. What Are The Advantages Of Ultrasonic Level Sensors?

Answer :

Many utility beverages have hard traits that negatively impact contact type sensor performance, protection and/or substitute expenses. Examples encompass corrosive, coating, scaling, viscous and dirty liquids. Ultrasonic sensors are non-touch, and therefore impervious to these characteristics.

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Question three. What Should I Avoid With Ultrasonic Level Sensors?

Answer :

The utility variables to avoid with ultrasonic are excessive foam, vapor, turbulence or set up in tall fittings with slim risers. Foam, vapor and turbulence can absorb and/or deflect away a huge portion of the go back sign. Tall riser fittings can disrupt the acoustic signal path. Appropriate product selection and installation is vital.

Question 4. What Does The four-20 Ma Signal Represent?

Answer :

The 4-20 mA represents the sensor’s dimension span. The 4 mA set factor is typically positioned close to the bottom of the empty tank, or the finest measurement distance from the sensor. The 20 mA set point is commonly located near the top of the whole tank, or the shortest size distance from the sensor. The sensor will proportionately generate a 4 mA signal whilst the tank is empty and a 20 mA sign whilst the tank is complete.

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Question 5. What Are The Benefits Of 4-20 Ma Signals?

Answer :

Analog four-20 mA signals have the subsequent benefits:

The equal -wires carry each the sensor electricity and signal; 4-20 mA is without difficulty transformed to a 1-five VDC enter via a 250 Ohm Watt resistor or 1-10 VDC enter thru a 500 Ohm Watt resistor; 4-20 mA is low current and therefore has a low heating loss thru the sign cord; and with shielded cable, 4-20 mA is noise immune to radiated and inducted interference.

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Question 6. What Is The Maximum 4-20 Ma Signal Distance?

Answer :

The sensor may be hooked up as much as one thousand ft from its point of termination using a shielded, 18-20 gauge twisted pair cable and 24 VDC power deliver. The total loop resistance ought to not exceed 900 ohms.(Changes from vendor to seller).

Question 7. Do I Have To Configure The four-20 Ma Measurement Span?

Answer :

While the 4 mA and 20 mA set factor configuration isn't always basically required, it’s advocated because it optimizes the sensor’s mounted performance.

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Question eight. Can I Reverse The Measurement Span From four-20 Ma To 20-four Ma?

Answer :

Yes, the sensor may be configured such that the 20 mA set point is empty and the 4 mA set factor is full.

Question 9. Can I Place A Loop Powered Level Indicator In Series With The four-20 Ma Signal?

Answer :

Yes, as long as the full loop resistance is less than 900 Ohms (Changes from vendor to supplier).

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Question 10. What Are Npt And G Mounting Threads And Where Are They Used?

Answer :

NPT (National Pipe Threads) are the American widespread tapered threads which are implemented in the course of North America, South America and elements of Asia. G (metric) ISO threads are the European fashionable directly threads carried out at some point of Europe and parts of Asia.

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Question 11. How Do I Select The Best Ultrasonic Level Sensor Range For Optimum Performance?

Answer :

Select a sensor variety that covers the tank top with as a minimum 25% margin. In challenging packages with light foam, vapor and/or turbulence, select a sensor variety this is double the tank top. The extra sensor will improve overall performance in such conditions.

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Question 12. What Are The Ultrasonic Level Sensor Materials Of Construction?

Answer :

Electronic enclosures are fireplace retardant polycarbonate, cables are polypropylene and transducers are PVDF. The mounting gasket is Viton.

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Question 13. How Do I Identify The Best Mounting Location For My Ultrasonic Level Sensor?

Answer :

The sensor must be positioned so that the acoustic signal path is freed from obstructions from facet-partitions, ladders, pipes, mixers and other units. The sensor ought to be established level and/or perpendicular to the liquid surface. If massive foam, vapor and/or turbulence are present, set up the sensor in a stand-pipe.

Question 14. What Types Of Installation Fittings Are Recommended For My Ultrasonic Level Sensor?

Answer :

The sensor can be broadly installed in tank adapters, couplings, flanges, brackets and stand pipes of suitable length relative to the transducer. Avoid fitting sorts that extensively recess the transducer into the right or compress the transducer in opposition to an inner pipe forestall. Use plastic fittings every time viable.

Question 15. How Tight Should My Ultrasonic Level Sensor Be Installed Within The Fitting?

Answer :

In maximum installations, the sensor is hand tightened handiest. If you operate a wrench or device, be cautious not to over-tighten the sensor within the fitting.

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Question sixteen. What’s The Maximum Flange Riser Height In Which My Ultrasonic Level Sensor Can Be Installed?

Answer :

The sensor may be increased as much as a most of 12″ excessive in a 6″ diameter riser, eight″ high in a four″ diameter riser, 6″ excessive in a three″ diameter riser and three″ high in a 2″ diameter riser.

Question 17. What’s The Best Pipe Id Size For Use In Installing My Ultrasonic Level Sensor In A Stand-pipe?

Answer :

Sensors with a 1″ transducer need to be hooked up in 2″ stand-pipes. Sensors with a 2″ transducer need to be set up in 3″ stand-pipes.

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Question 18. What’s The Best Way To Install My Ultrasonic Level Sensor On A Sloped Or Dome Top Tank?

Answer :

On plastic tanks, use a plastic self-aligning bulk head becoming that permits the sensor to be rotated perpendicular relative to the liquid floor. On metal or fiberglass tanks, use a plastic flange becoming with a short riser that comprises for the slope.

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Question 19. What’s The Best Way To Install My Ultrasonic Level Sensor With An Open Top Tank Or Sump?

Answer :

The facet mount bracket is a superb desire. Users can also fabricate equivalent brackets based on custom size or cloth requirements.

Question 20. Can I Install Two Ultrasonic Level Sensors In A Single Enclosed Tank?

Answer :

Typically best one sensor is hooked up according to tank. If you wish to install  sensors, the indicators have to be isolated to avoid pass-communicate interference. This can be completed through putting in one or each sensors in a stand-pipe.

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Question 21. Can My Ultrasonic Level Sensor Be Submersed In Liquid?

Answer :

NEMA 6 enclosure sensors are designed to resist infrequent submersion for quick periods of time. NEMA 4 enclosures are designed to withstand common splashing the equal of direct hose spray and ought to in no way be submerged. Generally speaking, the sensor have to be placed to avoid submersion and/or direct spray beneath everyday situations.

Question 22. How Do I Configure The Ultrasonic Level Sensor For My Application?

Answer :

Depending at the model, sensors are either configured the use of an critical display module or software program. Software is downloaded free to your pc and the sensor is configured thru our USB adapter.

Question 23. If Power Is Lost, Will The Ultrasonic Level Sensor Loose Its Configuration?

Answer :

No, the sensors have non-risky memory that can only be erased by way of appearing a factory reset.

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Question 24. What Does Factory Reset Do To The Ultrasonic Level Sensor?

Answer :

Factory reset erases any previous consumer configuration and returns the sensor to its original manufacturing facility set points.

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Question 25. The Ultrasonic Level Sensor Current Is zero Ma?

Answer :

Check the wiring for an open circuit and verify the energy supply.

Question 26. The Ultrasonic Level Sensor Current Jumps Between 19 Ma And 20 Ma?

Answer :

Check the set up fitting to make sure that its regular with our pointers. If the sensor is mounted in a steel becoming, transfer it to a plastic fitting.

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Question 27. The Ultrasonic Level Sensor Current Is > 22 Ma?

Answer :

Check the wiring for a brief circuit.

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Question 28. The Ultrasonic Level Sensor Jumps To A Lost Or Fail-safe Condition?

Answer :

Check the fill peak configuration set point. Make certain that the fill top placing corresponds to the tank full level (as measured from the empty tank bottom up), and now not the gap from the installed sensor to the liquid degree (as measured from the sensor down). What is variety, tank height, fill peak and useless band.

Check to make sure that the sensor is installed correctly. Check to make sure that there is no floor foam or obstructions in the beam course. If so, set up the sensor in a stand-pipe to separate its factor of size from the floor foam, dispose of the obstruction or relocate the sensor.

Question 29. The Ultrasonic Level Sensor Current Is Opposite Of The Liquid Level?

Answer :

Check the output at empty setting. Make positive that the desired placing is accurate with either 4 mA or 20 mA at empty.

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Question 30. What Are Ultrasonic Sensors?

Answer :

Ultrasonic sensors are business control gadgets that use sound waves above 20,000 Hz, beyond the range of human hearing, to measure and calculate distance from the sensor to a special target object. 

Question 31. How Does An Ultrasonic Sensor Work?

Answer :

The sensor has a ceramic transducer that vibrates whilst electrical power is implemented to it. The vibrations compress and extend air molecules in waves from the sensor face to a target object. A transducer both transmits and receives sound. The ultrasonic sensor will measure distance by emitting a sound wave and then "listening" for a hard and fast time period, taking into consideration the go back echo of the sound wave bouncing off the goal, earlier than retransmitting.

Question 32. When Would I Use An Ultrasonic Sensor?

Answer :

Because ultrasonic sensors use sound instead of mild for detection, they work in programs where photoelectric sensors may not. Ultrasonic sensors are a high-quality answer for clean object detection and for liquid stage size, applications that photoelectric sensors battle with because of goal translucence. Target color and/or reflectivity don't affect ultrasonic sensors which can function reliably in excessive-glare environments.

Question 33. When Should I Use An Ultrasonic Sensor Versus An Optical Sensor?

Answer :

Ultrasonic sensors provide benefits whilst sensing clean objects, liquid stage or particularly reflective or steel surfaces. Ultrasonic sensors additionally characteristic well in moist environments wherein as an optical beam may additionally refract off the water droplets. However, ultrasonic sensors are liable to temperature fluctuations or wind. With optical sensors, you could also have a small spot size, speedy response and in a few instances, you may venture a visible spot on a goal to help with sensor alignment.

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Question 34. How Do Ultrasonic Sensors Deal With Noise And Interference?

Answer :

Any acoustic noise on the frequency to which the ultrasonic sensor is receptive, might also intrude with that sensor's output. This includes high-pitched noises which include those created via a whistle, the hissing of alleviation valves, compressed air or pneumatic gadgets. You might also get acoustical crosstalk through locating two ultrasonic sensors of the equal frequency close collectively. Another type of noise, electric noise, isn't extraordinary to ultrasonic sensors.

Question 35. What Environmental Conditions Affect An Ultrasonic Sensor?

Answer :

Temperature fluctuation affects the rate of an ultrasonic sensor's sound waves. As temperature increases, the sound waves tour quicker to and from the goal. While the target may not have shifted, it will seem to the sensor that the goal is closer.  Air currents because of pneumatic gadget or fanatics can also deflect or disturb the direction of the ultrasonic wave. This should lead a sensor to fail to recognize the precise place of a goal.

Question 36. Why Do I Need To Let My Ultrasonic Sensor Warm Up Before I Operate It?

Answer :

The ultrasonic sensor have to no longer be configured or operated till it has had a chance to heat up. When a sensor is first powered up, the person components warmth up and additionally warmth the encompassing area and components. This fluctuation in temperature from a cold begin to the working temperature is referred to as "Warm-Up Drift." Until all additives have stabilized at the best operating temperature, the accuracy of your measurements may be affected.

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Question 37. What Is A Dead Zone?

Answer :

A dead region refers to the area directly in the front of the transducer face where the sensor can not reliably make measurements. This is because of a phenomenon known as ringing. Ringing is the ongoing vibration of the transducer after the excitation pulse. The strength have to deplete earlier than the transducer can listen for a go back echo. Make sure to locate your target outside of the desired lifeless area of your ultrasonic sensor.

Question 38. Are Ultrasonic Sensors Slower Than Photoelectric Sensors?

Answer :

Yes. The speed of sound is appreciably slower than the speed of mild, consequently an ultrasonic sensor, through its very nature, might be slower than an optical sensor.

Question 39. What Sorts Of Targets Should I Avoid When Using An Ultrasonic Sensor?

Answer :

The first-class objectives for use with an ultrasonic sensor are big, flat, stable surfaces of substances together with metal, ceramic, glass or timber. Placement ought to constantly be perpendicular to the sensor. Soft or irregular floor goals, inclusive of pellets, sawdust or foam should be prevented.

Question 40. What Is The Best Way To Detect Randomly Placed Objects Using An Ultrasonic?

Answer :

Teach the sensor the "historical past" as your properly condition. By teaching an ultrasonically reflective heritage surface as the good condition, any item getting among the sensor and the heritage might be detected, consequently inflicting the output to exchange.

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