Analysis of Common Installation Errors and Misuse of Density Meters

1、 Installation error

1. Horizontal installation of online density meter
   Online density meters typically operate based on static pressure principles, such as the double flange differential pressure method. If installed horizontally, it can cause uneven distribution of liquid static pressure, leading to measurement errors. For example, a certain enterprise installed LK-ZXMD3051 densitometer, which caused fluctuations in readings due to horizontal installation. The problem was resolved after vertical installation.
   correct approachVertical installation ensures that the two pressure relays are on the same vertical plane to avoid the influence of flow rate fluctuations.

2. No auxiliary measuring tank installed
   Directly installing a density meter in a liquid environment with high flow or vibration can result in unstable readings. For example, when no auxiliary tank is installed, the fluctuation of circulating liquid will interfere with static pressure measurement.
   correct approachInstall auxiliary tanks in scenarios with high flow rates or large vibrations to ensure that the density meter operates in a stable flow rate area.

3. There is a blind spot in the installation location
   When installing an ultrasonic density meter, if the angle between the radiation surface of the probe and the cross-section of the catheter is too small (exceeding the acute angle of the transducer), or the installation position is unreasonable, it will cause measurement blind spots. For example, a certain ultrasonic level gauge may experience full range or arbitrary data due to its installation position being too high.
   correct approachReasonably choose the installation height to ensure that the angle between the probe radiation surface and the conduit section meets the requirements.

2、 Misuse operation

1. Not zeroed or calibrated
   The density meter needs to undergo weight calibration (zeroing) before use, otherwise the test results will be inaccurate. For example, a density tester may cause measurement values to deviate due to direct testing without zeroing.
   correct approachBefore moving the position or changing the sample each time, use standard weights for zeroing operation.

2. There are bubbles on the surface of the sample
   When testing the density of solids or liquids, if bubbles adhere to the surface of the sample, it can cause the volume measurement to be larger and the density value to be smaller. For example, if the particle sample is placed in water without breaking the bubbles, the density test result will be lower than the true value.
   correct approachBefore testing, clean the surface of the sample with alcohol or use tweezers to break through any bubbles.

3. Accessories not reset to zero
   When testing solid particles, if accessories (such as tennis balls) are not reset to zero and used directly, it will result in quality measurement errors. For example, in a certain experiment, the density deviation reached 5% due to the tennis ball not being cleared.
   correct approachPut the accessory into water, reset it to zero after the value stabilizes, and then put it into the sample for testing.

4. electrostatic interference
   Samples containing static electricity placed directly on the density meter may affect the accuracy of the weighing sensor. For example, plastic particles adsorb dust due to static electricity, resulting in larger mass measurements.
   correct approachEliminate static electricity from the sample before testing (such as using an anti-static brush), or choose a density meter made of anti-static material.

Analysis of Common Installation Errors and Misuse of Sound Velocity Instruments

1、 Installation error

1. The transmitter and receiver end faces are not parallel
   The transmitter and receiver end faces of the ultrasonic sound velocity meter must be strictly parallel and perpendicular to the track, otherwise it may cause signal attenuation or measurement failure. For example, in a certain experiment, due to the tilted end face, the receiver was unable to capture the signal.
   correct approachAdjust the screws to make the end faces parallel and calibrate the perpendicularity with a level.

2. Cable entanglement
   When the receiver is in motion, the connecting cable is prone to getting tangled around the guide rail or photoelectric door, causing damage to the equipment. For example, in a certain experiment, the receiver motor burned out due to cable entanglement.
   correct approachManually straighten the cables or fix them with anti winding brackets.

3. Receiver exceeds limit
   When the receiver moves beyond the limit of the guide rail, the controller display screen will show "8.8.8.8.8", causing measurement interruption. For example, in a certain experiment, data acquisition failed due to the receiver not being reset.
   correct approachMove the receiver between the two limit positions and restart the device.

2、 Misuse operation

1. Unrecorded or incorrectly selected source frequency
   The source frequency of the sound velocity meter (such as 37420Hz) needs to be set according to the equipment label, otherwise it will cause Doppler effect calculation errors. For example, in a certain experiment, the deviation of sound velocity measurement value reached 10% due to selecting the wrong frequency.
   correct approachSearch for the source frequency labeled on both sides of the guide rail and accurately set it in the menu.

2. The ultrasonic end face is not perpendicular to the track
   When the end face of the transmitter or receiver is not perpendicular to the track, the ultrasonic propagation path deviates, which affects the measurement accuracy. For example, in a certain experiment, due to the inclination of the end face, the sound velocity value fluctuated by more than 5%.
   correct approachAdjust the end face angle to ensure it is perpendicular to the track.

3. Uncalibrated proportional coefficient
   The sound velocity meter needs to calculate the proportionality coefficient (k) between frequency and velocity through multiple measurements. If the default value is used without calibration, it will cause system errors. For example, due to an uncalibrated k value, the sound velocity measurement results of a certain device are systematically low.
   correct approachMeasure multiple times according to the experimental steps and calculate the value of k using the least squares method.