VISCOMETER, OFI, 8-SPEED, MODEL 800 PART No

Transcription

1 OFI Testing Equipment Viscometer, 8 Speed, Model 800 Instructions Part # Page 1 of 4 VISCOMETER, OFI, 8-SPEED, MODEL 800 PART No The model 800 eight speed electronic viscometer is designed and exclusively manufactured by OFI Testing Equipment, Inc. It is extensively used worldwide in both the field and laboratory for the precise measurement of rheological properties of fluids. Eight precisely regulated test speeds are provided by the OFI pulsed-power electronic speed regulator. The use of low power C-Mos electronic circuitry makes the model 800 viscometer ideally suited for field operation from a 12 volt battery or from standard rig power. The electronic speed regulator continuously monitors and automatically adjusts the rotational speed to maintain a constant shear rate under varying fluid shear conditions and input power variations that are commonly found on-site. The eight speeds are 3 (gel), 6, 30, 60, 100, 200, 300 and 600 RPM. A higher stirring speed is provided and speeds may be changed without stopping the rotor with a control knob selection switch. Shear stress data is continuously displayed via a lighted magnified dial which eliminates glare and makes readings easier to see. Operation: 1. Place a fresh sample of drilling fluid in any suitable container and immerse the rotor sleeve exactly to the scribed line by raising the platform and firmly tightening the lock nut on the platform. 2. Plug the viscometer into the power supply and turn on the power to the viscometer by flipping the On/Off switch located on the back of the viscometer. CAUTION: If using a thermostatically temperature controlled viscosity cup, the Maximum operating temperature is 200 F (93 C). Liquid trapped inside a hollow Bob may vaporize when immersed in very high temperature fluids and cause the Bob to explode. 3. Rotate the speed selector knob to the stir setting and mix the sample for a few seconds while heating or cooling the fluid to the desired temperature as measured with a thermometer. Rotate the knob to the 600 RPM setting, wait for the dial to reach a steady reading, and record the 600 RPM reading and temperature of the sample. 4. Rotate the speed selector knob to the 300 RPM setting, wait for the dial to reach a steady reading and record the 300 RPM reading.

2 OFI Testing Equipment Viscometer, 8 Speed, Model 800 Instructions Part # Page 2 of 4 5. Rotate the speed selector knob back to the stir setting and re-stir the sample for a few seconds. 6. Rotate the speed selector knob to the gel setting and immediately shut off the power. 7. As soon as the sleeve stops rotating, wait 10 seconds and turn the power on while looking at the dial. Record the maximum dial deflection before the gel breaks as the 10 second gel strength. 8. For the 10 minute gel strength re-stir the fluid and wait 10 minutes before recording the maximum dial deflection. 9. When readings at other speeds are desired, always make the measurements from the higher RPM down to the lower RPM. For example, if readings are also desired at 200 RPM and 100 RPM, the order of measurement should be: Stir, 200 RPM, 100 RPM dial readings and then the gel strengths, if needed. Calculations: Plastic Viscosity (PV), cp Yield Point (YP), lb. / 100 ft 2 = 600 RPM reading RPM reading = 300 RPM reading - Plastic Viscosity (PV) Apparent Viscosity (AV), cp = 600 RPM reading 2 Gel Strength, 10 second, lb / 100 ft 2 Gel Strength, 10 minute, lb / 100 ft 2 = the maximum dial deflection after 10 seconds = the maximum dial deflection after 10 minutes Power Requirements: 115 Volt, 50 / 60 Hz or 12 Volt DC 230 Volt, 50 / 60 Hz or 12 Volt DC Note: For longer lasting continuous operation it is strongly recommended that the model 800 viscometer be used with the OFI power supply only. No other power supply now available has the filtering range to assure true frequency under varying input power conditions. Size: Height - 20 inches (50.8 cm); Width - 6 inches (15.2 cm); Depth inches (19.7 cm) Weight: Viscometer - 13 lbs (5.8 kg) Power Supply - 1 lbs 2 oz (0.5 kg) Remarks: 1. The sleeve, bob and splash guard should be washed and dried after each operation. 2. Keep the instrument upright at all times especially when cleaning so that water does not get into the bearings. Never immerse the rotor sleeve in fluids above the scribed line. 3. When measuring gel properties, the dial does not have to return to zero during the quiescent period. Therefore, it should not be forced back to the zero setting if it does not freely do so. When determining the maximum dial deflection, no allowance needs to be made if the dial did not start at zero. Only the maximum dial deflection is of interest. Rheological properties and characteristics of the sample will determine if the dial returns to zero during the quiescent periods of the gel measurements.

3 OFI Testing Equipment Viscometer, 8 Speed, Model 800 Instructions Part # Page 3 of 4 4. The viscometer should have a zero dial reading when placed in an upright position with the sleeve not immersed in fluid prior to running tests. With the instrument in this position, rotate the sleeve at 600 RPM. The dial reading in air should not exceed one. Place water in a suitable container and immerse the rotor sleeve to the scribed line. Rotate the sleeve at 600 RPM. The dial reading in water should be between 1.5 and 3.0. At 300 RPM the dial reading in water should be between 0.5 and 2. Failure of the viscometer to pass any one of the above tests indicates that the bearings are bad and should be replaced by a qualified instrument technician. Calibration Check Procedure Equipment # Calibration Check Kit # Calibrating Instrument for 8-Speed Viscometer (Requires a trained technician) Calibration Fluids, "Certified" # Calibration Fluid, 20 cp, 16 oz # Calibration Fluid, 50 cp, 16 oz # Calibration Fluid, 100 cp, 16 oz # Calibration Fluid, 200 cp, 16 oz # Calibration Fluid, 500 cp, 16 oz Procedure 1. Choose the certified calibration fluid with a chart (viscosity vs. temperature) to cover the viscosity range of interest. Make sure the lot number on the chart matches the lot number on the fluid container. Each lot of standard fluid is individually certified. The viscosity will normally vary slightly from lot to lot. 2. Clean and dry the viscometer bob, rotor and cup. Place the viscometer and the calibration fluid side-byside on the counter top in a room with a reasonably constant temperature [<5 F (<2.7 C)]. Allow the viscometer and the fluid to stand at least 2 hours to equilibrate. 3. Operate the viscometer in Air for two to four minutes to loosen up bearings and gears. Observe the rotor sleeve for excessive wobbling and correct if necessary. 4. Fill the cup to the prescribed line with calibration fluid and place it on the viscometer stage. Move the stage upward until the fluid level is to the inscribed line on the rotor sleeve. 5. Place a thermometer capable of ±0.2 F (0.1 C) into the fluid and hold or tape it in place to prevent breakage. Operate the viscometer at a low speed setting until the thermometer reading becomes stable to within ±0.2 F (0.1 C) per 30 seconds. Note and record the temperature reading.

4 OFI Testing Equipment Viscometer, 8 Speed, Model 800 Instructions Part # Page 4 of 4 6. Once the temperature has stabilized, operate the viscometer at 600 rpm and then at 300 rpm. Note and record the dial readings to the nearest 0.5 dial unit. 7. Using the temperature-viscosity chart supplied with the calibration fluid, determine the certified viscosity to the nearest 0.5 centipoise. A. Compare the 300 rpm reading to standard viscosity and record the deviation plus or minus. B. Divide the 600 rpm dial reading by 1.98, compare that to standard viscosity and record the eviation plus or minus. 8. Deviations exceeding 1.5 dial units are not acceptable. If the deviation exceeds this tolerance, the viscometer will require adjustments or calibration by a qualified technician. 9. Record the viscometer serial number, date and deviation. Mark on the viscometer the date of calibration and a general indication of the calibration check status.

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