Ultrasonic Flowmeter Upgrading Project

On March 2009, we upgraded our GE ultrasonic flowmeter from type of XMT868 to XMT868i and equipped with the surge arrester.

It was found that the fuse on the old meter electronic card was blown. After replaced the meter was OK. However, after that, the old meter was suddenly off temporarily, after which it was back to OK again and it happen several times.

Considering its important function to measure how many filtered produced water injected to the wells for enhanced oil recovery program, we decide to replace it with the new one equipped with the surge arrester as suggested by engineer from GE.

Configuring the meter          The new GE XMT868i 

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Published in: on June 10, 2009 at 10:05 am  Leave a Comment  

Bimetallic Temperature (Thermometer) Devices

Measurement of temperature normally requires close, direct contact between the material and the sensor in such a manner that the sensor responds quickly to the temperature of the material.

OPERATING PRINCIPLES

The bi-metallic element consists of two strips of different metals, with different thermal expansion coefficients, inseparably joined together. This strip is spirally or helically wound with one end fixed to the body of the thermometer, and the other attached to the axis of a pointer. Measurement of temperature is made with the bi-metallic system inside the temperature sensor. Temperature variation influences the bi-metallic strip such as to rotate the pointer; this rotation is indicated on a dial.

 

 INSTALLATION

The thermometer should be mounted at any convenient location where it will be subjected to the average temperature variations to be indicated.

Avoid bending the stem as this will cause misalignment of the internal parts, resulting in undue frictional errors.

To tighten the thermometer to the apparatus, use a wrench applied to the hexagon head of the threaded connection located just outside of the case.

Locate the stem so that at least two inches will be subjected to the average temperature to be measured.

Exposing the stem to a temperature in excess of the highest dial reading should be avoided.

The thermometer is normally provided with a threaded connection. To tighten the thermometer to the apparatus or into the well, use an open-end wrench applied to the hexagon head of the threaded connection. Turn until reasonably tight, then tighten still further in the same manner as a pipe elbow or similar pipe fitting until the scale is in the desired position for reading. DO NOT TIGHTEN BY TURNING THE THERMOMETER CASE.

Install the dry type thermometer so that the maximum case temperature is kept below 200°F at all times.

Install the liquid filled type thermometer so that the maximum case temperature is kept below 150°F at all times.

When a thermometer is equipped with a well, the well should be installed onto the apparatus first. The stem of the thermometer should then be coated with a heat conducting medium (a mixture of glycerin and graphite or vaseline or any other heavy lubricant may be used), after which the thermometer stem is inserted, and tightened into the well.

CAUTION: Thermowells should be used on all pressurized applications, to protect the thermometer from corrosion or physical damage, and to facilitate removal of the thermometer without disturbing the process.

TESTING AND CALIBRATION

Bimetal Dial Thermometers are carefully calibrated at the factory and under most operating conditions will retain their accuracy indefinitely. However, as in the case of all instruments, it is well to make periodic checks for accuracy against known standards.

 ASME B40.3 STANDARD ACCURACIES*

Thermometer accuracy is graded as shown in the table below. Adjustment of the case of a thermometer, with an adjustable angle connection, may affect its accuracy. This effect should not exceed 0.5% of span.

*ASME B40.3 may be ordered from American Society of Mechanical Engineers, Three Park Avenue, New York, NY 10016.

 

Example #1:  Range 0/250°F Grade A

  Span = 250-0 = 250°F

Accuracy at    20% of span (50°F) = ±1% = ±2.5°F

Accuracy at    50% of span (125°F) = ±1% = ±2.5°F

Accuracy at    100% of span (250°F) = ±1% = ±2.5°F

Example #2:  –40/160°F Grade E

  Span = 160-(–40) = 200°F

Accuracy at    20% of span (0°F) = ±3.4% = ±6.8°F

Accuracy at    50% of span (60°F) = ±1% = ±2.0°F

Accuracy at    100% of span (160°F) = ±5% – ±10.0°F

Example #3:  Range 50/300°F Grade AA

  Span = 300-(–50) = 250°F

Accuracy at    0% of span (50°F) = ±1% = ±2.5°F

Accuracy at    50% of span (175°F) = ±0.5% = ±1.25°F

Accuracy at    70% of span (225°F) = ±0.7% = ±1.75°F.

 ADJUSTMENT

If it is necessary to make an adjustment to the thermometer proceed as follows:

On thermometers fitted with an “External Adjustment”

– Use a small wrench, small screwdriver or a coin to turn the slotted hexagon head in the back of the case until the pointer indicates the proper temperature on the dial.

MAINTENANCE OF DIAL THERMOMETERS

Aside from occasional testing, little or no maintenance is required.

Be sure that the gasketed glass cover is on the case at all times, as moisture and dirt inside the case will eventually cause the thermometer to lose its accuracy.

If the thermometer is used for measuring the temperature of a material that may harden and build up an insulating layer on the stem, the thermometer should be removed from the apparatus occasionally, and the stem cleaned. Observe this precaution to ensure the sensitivity of the instrument.

(Courtesy of the Ashcroft and its related manuals)

Published in: on October 14, 2008 at 9:12 pm  Leave a Comment  

Temperature Measurement

How can we measure temperature?

Temperature can be measured via a diverse array of sensors. All of them infer temperature by sensing some change in a physical characteristic. The types of the sensor commonly found in industry are (1) bimetallic temperature devices, (2) resistive temperature devices (RTDs and thermistors), (3) thermocouples, and (4) infrared thermometer.

The detail discussions on each will be on the near incoming posts. So, stay tuned…

Published in: on September 21, 2008 at 9:33 am  Leave a Comment  

What is Temperature?

Looking for definition of temperature from the textbook or even website is not so easy. I found clearer definition of it compare to the others explained on the The HyperPhysics Web site at Georgia State University, author R. Nave.

The temperature is defined from the kinetic theory so called the kinetic temperature. It is found also that the fact that temperature is not heat and what temperature scales are. One knows it’s related to heat and there is a difference between them.

Temperature: A convenient operational definition of temperature is that it is a measure of the average translational kinetic energy associated with the disordered microscopic motion of atoms and molecules.

Temperature is not directly proportional to internal energy since temperature measures only the kinetic energy part of the internal energy, so two objects with the same temperature do not in general have the same internal energy.

Internal Energy Example

When the sample of water and copper are both heated by 1°C, the addition to the kinetic energy is the same, since that is what temperature measures. But to achieve this increase for water, a much larger proportional energy must be added to the potential energy portion of the internal energy. So the total energy required to increase the temperature of the water is much larger, i.e., its specific heat is much larger.

The flow of heat is from a high temperature region toward a lower temperature region.

When a high temperature object is placed in contact with a low temperature object, then energy will flow from the high temperature object to the lower temperature object, and they will approach an equilibrium temperature.

Temperatures are measured in one of the three standard temperature scales (Celsius, Kelvin, and Fahrenheit).

The Celsius, Kelvin, and Fahrenheit temperature scales are shown in relation to the phase change temperatures of water. The Kelvin scale is called absolute temperature and the Kelvin is the SI unit for temperature.

The triple point of water is 273.16 K, and that is an international standard temperature point. The freezing point of water at one atmosphere pressure, 0.00°C, is 0.01K below that at 273.15 K. If you want to be really precise about it, the boiling point is 373.125 K, or 99.75 °C. But for general purposes, just 0 °C and 100 °C are precise enough.

Published in: on September 16, 2008 at 6:50 am  Leave a Comment  

The Crab Mania

On the way back to Surabaya from Malang, we had lunch at the Kepiting Cak Gundul (The Cak Gundul’s Crabs). As you can see, I was too buzy eating the crabs. No time to share with you the whole story. Sorry, guys…

Published in: on September 12, 2008 at 8:46 am  Leave a Comment