Heavy Hammer Level Guage

Heavy Hammer Level Guage

The ULZC type weight-based level gauge can be used to measure the level of powdered, granular, and lumpy solid materials in silos, allowing users to reliably monitor the material level in the silo. The level gauge consists of a sensor and a control and display instrument. The sensor design incorporates the advantages of similar products at home and abroad. Its unique structure and transmission method overcome many of the problems frequently encountered in other types of weight-based level gauges, resulting in reliable operation, low maintenance, and wide applicability.
Detailed Introduction:
I. Overview
The ULZC type weight-based level gauge can be used to measure the level of powdered, granular, and lumpy solid materials in silos, allowing users to reliably monitor the material level in the silo.
The level gauge consists of a sensor and a control and display instrument. The sensor design incorporates the advantages of similar products at home and abroad. Its unique structure and transmission method overcome many of the problems frequently encountered in other types of weight-based level gauges, resulting in reliable operation, low maintenance, and wide applicability. (Figure 1)

Figure 1. Internal Structure Schematic Diagram
The control display uses a 16-bit microcontroller.  The microcontroller controls the entire detection process of the sensor, detects its signals, performs calculations, displays the material level digitally on the display window on the panel, and provides a corresponding 4-20mA analog current signal output. Measurement can be performed automatically at regular intervals or manually.
Display controller (secondary instrument, see Figure 2)

II. Main Technical Specifications
1. Sensor
Measurement Range: 0–10m; 0–20m; 0–30m; 0–40m; 0–50m (Special specifications can be customized)
Measurement Accuracy: ±1.5cm (±1.5cm for each counting pulse)
Repeatability: ±1%
Resolution: ±1.5cm
Detection Speed: 0.15m/s
Medium Temperature: -40℃～+100℃; -40℃～+300℃; 300℃～+1000℃ (Temperature must be specified when ordering)
Motor Stall Torque: 5N.m
Measuring Cable: ф2 stainless steel wire rope {Material 304 (suitable for temperatures below 300℃ to prevent long-term high-temperature oxidation) or Material 2520 (suitable for temperatures below 1000℃ to prevent long-term high-temperature oxidation)}
Weight of Counterweight: 1–3Kg (set according to the measuring range)
2. Control and Display Instrument (Horizontal Type)
Power Supply Voltage: 220VAC±10% 50Hz±1Hz
Power Consumption: 15W at rest; 60W / 90W / 120W / 180W during operation (related to motor selection)
Ambient Temperature: -40℃～+80℃
Digital Display: 0.00～50.00 (m) 4-digit LED
Pulse Display: Displays the percentage of the measuring range
Current Output: 4～20mA (active output, no need for external DC24V power supply)
Output Signal Accuracy: ±0.5%
Timing Time: 10–9999 minutes (or as required by the user)
Maximum Distance to Sensor: 0.5km
Weight: 1.5kg
Dimensions: Width 158 × Height 79 × Length 142
Opening Size: Width 152 × Height 76
III. Working Principle
The detection process of the level gauge sensor installed on the top of the silo is controlled by signals from the control and display instrument. The sensor consists of a reversible motor, worm gear, worm screw, lead screw, gear shaft, winding drum, and sensitive lever, etc. (See Figure 1)
When the sensor receives a detection command: the motor rotates forward, and after deceleration through the worm gear and worm screw, it drives the gear shaft and winding drum to rotate, causing the steel wire rope to lower, driving the weight down from the top of the silo. When the weight reaches the material surface, it is supported by the material surface and loses weight, the steel wire rope slackens, and the sensitive lever activates the microswitch. The control display receives this signal and immediately issues a reverse rotation command to the motor. The weight rises and returns until the winding drum touches the top limit switch, the motor stops, and the weight returns to its original position at the top of the silo, completing one detection process.
During this process, the control display instrument calculates the distance from the bottom of the silo to the material surface by detecting the number of rotations of the winding drum, displays the digital value on the panel, and outputs a 4-20mA current signal at the rear panel terminals.
IV. Installation and Wiring
1. Installation of the Primary Instrument
(1) Select a suitable location on the silo roof for installing the level meter:
The measurement point should be away from the feed inlet and discharge outlet, and should be chosen as close as possible to a location where the measurement is approximately at the same height during both loading and unloading processes.
On dome-shaped cement and fly ash silos, the installation location should be chosen away from the soot blowing pipe, not on the same line as the soot blowing pipe, and at a distance of 2/3 of the radius from the center of the silo roof.
On coal powder silos in power plants, in order to better compare with the data from the original manual probe, a location closer to the original manual probe should be selected.
The measurement point should be free of iron frames or other debris below to avoid obstructing the measurement.
(2) Prepare the flange, steel plate, and steel pipe (See Figures 3, 4, and 5)

a. Flange

Figure 3 (Flange)

b. Steel plate
The steel plate is approximately 300 x 500 mm in size. This plate is not needed for sheet metal silo roofs, but should be prepared for concrete silo roofs. A hole should be drilled in the steel plate, with a diameter equal to the outer diameter of the steel pipe and a thickness δ = 8–10 mm. (See Figure 4)

Figure 4 (Steel plate)

C. Steel pipe
If the silo is outdoors, a frost protection cover is required, so the height of L after being fixed to the silo roof should be approximately 100mm. If the silo is located inside a building, the height can be extended to 300-400mm. (See Figure 5)

Figure 5 (Steel pipe)

(3) Welding:

● Sheet metal silo roof:

Weld the flange to the steel pipe, ensuring they are perpendicular to each other.  Drill a hole in the appropriate location on the silo roof, with a diameter equal to the outer diameter of the steel pipe. Weld the steel pipe to the circular hole in the silo roof. (See Figures 6 and 7)  Ensure the flange is level using a spirit level.

● Cement Silo Roof:
Weld the flange, iron pipe, and iron plate together, ensuring they are perpendicular to each other (see Figures 8 and 9). Drill a hole in a suitable location on the silo roof, with a diameter of approximately 100 mm. Then place the iron plate over the hole and fix it to the cement silo roof. It is recommended to seal it with concrete. Ensure the flange is level using a spirit level.
During installation, also pay attention to the relative position of the square shape of the level sensor and the four holes of the flange. That is, when fixing the flange, consider the orientation of the holes to ensure the level sensor is at a suitable angle on site (see Figure 10).

                                            Figure 8                                                                                                 Figure 9                                                                               Figure 10

(4) Install the primary meter: (See Figure 12)

Install the bracket onto the flange.

Open the seal at the bottom of the instrument, untie the knot securing the pre-reserved steel wire rope, and release the wire rope. Be careful not to let the rope loosen or get damaged.
Thread the steel wire rope through the funnel of the bracket and fix the level gauge to the bracket.
Remove the aluminum plate from below the bracket and thread it onto the steel wire rope. Thread the small copper tube onto the steel wire rope. Thread the steel wire rope through the ring, and loop the ring through the hole in the weight. Flatten the copper tube to secure the steel wire rope. Be careful not to damage the rope. Insert the weight into the silo and cover it with the aluminum cover. (See Figure 11)

The length of the steel wire rope should be such that the hammer is positioned 200mm below the top of the silo. First, measure the thickness of the silo roof; the required length is the roof thickness plus 200mm.

5) Inspection of the Primary Meter

To avoid damage caused by transportation impacts, the primary meter must be carefully inspected before commissioning. First, open the sealing cover.

a. The steel wire rope should be neatly arranged around the large drum and correctly threaded between the two guide wheels (see Figure 13).

b.Check top switch                           ↓              ↓     1#     2#    3#    4#

                                                                                   Figure 13 

Using a multimeter, measure terminals 2# and 4#.  They should be open when the hammer is present. Reach into the bracket and lift the steel cable upwards. The small swing arm driven by the spring should cause the small switch to make contact. At this point, the multimeter should indicate that terminals 2# and 4# are connected. When you release your hand, the small switch should open again. This indicates a normal state (see Figure 14).  The following describes possible fault symptoms indicated by the fault display:

          Figure14

It has been confirmed that there is material in the silo, but the sensor indicates that there is no material in the silo. Please check if the limit switch is damaged and if the connecting wires between the primary and secondary meters are normal and reliable.
If the system is set to automatic measurement but no measurement is performed within the specified time, please perform a manual measurement. If the hammer position digital display shows no change, please check if the limit switch is always closed, if the weight has fallen, and if the connecting wires between the primary and secondary meters are faulty.

                             Figure 15

Is the motor damaged? Can it return to normal operation after the secondary meter is repowered? It should be in a normal state. (See Figure 14)

                             Figure 16 

Use a multimeter to measure terminals 3# and 4#. In the normal, stationary state, the weight should be in the fully raised position, and terminals 1# and 2# should be connected. (See Figure 15)

b.Check bottom switch                  ↓                                  ↓     1#       2#         3#       4#

                                                   Figure 13

Use a multimeter to measure terminals #1 and #4. Confirm that there is no power supply. Manually rotate the motor shaft counterclockwise at the motor connection point, causing the large cylinder to rotate towards the hammer release direction. As the hammer lowers and the large cylinder moves to the right, continuously check the connection status of terminals #1 and #4 while rotating. The rhombic small magnet should rotate one full turn, and terminals #1 and #4 should be connected twice. (See Figures 16 and 17)

2. Installation of the Secondary Meter
Pull out the drawer. Pressing the spring on the top will open the drawer. Set the 8-position small switch on the main board according to the specific instructions. Check if all connectors are loose. Fix the meter in the designated position.

3. Wiring
First, carefully check the wiring and connect according to the diagram. (See Figure 18) The shielded cable connecting the primary meter terminal block to the secondary meter is 4-core × 1.0mm (RVV4×1.0) and 3-core × 1.0mm (RVV3×1.0) (terminals #5, #6, and #7 should be wired separately to prevent interference). Terminals #1 to #7 of the primary and secondary meters must correspond one-to-one.
Primary meter terminal block

Secondary wiring diagram

                                                              Figure18

Note: 1#: Pulse, 2#: Bottom (lower limit), 3#: Top (upper limit), 4#: Common, 5#: Power supply, 6#: Rising edge, 7#: Falling edge (All wires connected to the secondary meter require shielded cables, as the pulse signal is susceptible to interference)
V. Setting of Measurement Range, Time, and Alarm
Press the Setting 1 button to enter the setting menu, which displays H L. Press the Setting 3 button to display the original setting data in the menu. Pressing the Setting 3 button again will cause the flashing digit to shift (move one position). Press the Setting 2 button to increment the flashing digit by 1 (0-9 cycle).

VI. Operation and Maintenance
Before officially powering on the instrument, first confirm that the instrument installation is correct: use a multimeter to check whether the bottom limit switch, top limit switch, and power switch are working properly.
Check if the reed switch is damaged. With the power off, manually rotate the worm gear (the part connected to the motor).  The reed switch should open and close twice for every full rotation. If not, the position of the reed switch and the magnetic frame needs to be adjusted to ensure the reed switch opens and closes twice for every full rotation of the worm gear. Then check that the 7 connections between the primary and secondary instruments correspond one-to-one. They must correspond exactly, otherwise the secondary instrument will not work or may even be damaged, and the primary instrument may experience malfunctions such as tangled wires.
Manual Detection
Press the manual detection button (setting 3) to perform a detection: The process is as follows: The motor drives the weight down, and the digital display gradually decreases from the full range until the weight touches the material surface, at which point the number stops decreasing. This number represents the height of the material level in the silo. The weight automatically returns to the top of the silo. The current output value reflects the corresponding material level height.
This level gauge has many methods to prevent dust from entering the sensor, and different installation structures are used depending on the application. If there are special requirements, they should be specified when ordering, such as material type, whether there is pressure, whether there is water vapor, etc. When used in dusty environments, a purging device can be used.  Regular cleaning should be performed as needed. There is a large opening behind the rotating drum and another opening in the front; a brush or other tools can be used to clean out any dust inside.
VII. Special Precautions
1. During the operation of the primary instrument, do not operate any buttons on the secondary instrument, otherwise the secondary instrument will be damaged.
2. When the customer requests automatic operation, to extend the service life of the motor, the interval time should be no less than 15 minutes for 0-10 meters, no less than 20 minutes for 0-20 meters, no less than 30 minutes for 0-30 meters, no less than 40 minutes for 0-40 meters, and no less than 50 minutes for 0-50 meters.

Certificate  Approved