EZ-Flo Low Profile Flow Scale Owners Manual
(Patented)—Copyright 2016 Rev. 4-10-19
3908 Tonkawood Road, Minnetonka, MN 55345
Phone: 952-939-6000 Email: david@clarencerichard.com Web: www.EzFloWeighing.com
Index..
Expectations – Page 1
Shipping/Receiving - Page 3
Installation –Page 6
Set Up – Page 8
Electrical – Page 15
Operation- Page 16
Programming – Page 17
Calibration- Page 18
Troubleshooting- Page 21
Drawings- Page 29
Optional Equipment- See Price List
FLOW SCALE EXPECTATIONS.
Proper installation and maintenance are very important parts of operation.
FLOW SCALES are becoming an important part of most bulk material
handling facilities. However, being relatively unobtrusive in most conveyor systems, they
are often overlooked or ignored after their initial installation. Lack of simple maintenance
will potentially cause significant reduction in the accuracy capabilities of these
instruments. Most belt conveyor scales are capable of providing reliable results.
Regardless of the accuracy capability of the scale design, it is unlikely that these devices
will perform as promised if simple maintenance procedures are not strictly adhered to.
Every scale installation will develop its own set of operating characteristics; therefore, it is absolutely necessary to monitor the scale’s performance and provide routine
maintenance as required. It is generally advised, throughout the belt scale industry, that
calibration checks be made frequently during the weeks after initial installation, then to
increase the time frame between calibrations as statistical results are obtained. While
this is a simple suggestion to follow, all too frequently the increase in time between
calibration verifications defaults to only whenever a problem is suspected. By then it is
too late, incorrect weighing was made, processes have been interrupted, mix has been compromised and inventory levels need other means of verification.
Establishment of a routine inspection procedure, including not only the flow
scale, but the entire material handling system, will result in an increased confidence in
the scale and ultimately greater control of the accuracy it is providing. It is important to
remember that the entire conveyor that the belt scale is installed in becomes part of the
“weighing system,” and that any changes that occur or are performed within this
conveying system can and probably will affect the performance of the scale. Therefore, in addition to a routine scale maintenance procedure it becomes imperative that any and all maintenance performed on the conveyor be reported to the individual or department
responsible for the scales performance.
Please see recommended Maintenance Check List chart. Note that verification of the
basic mechanics of the conveyor system itself is an integral part of the scale
maintenance procedure.
Typical Flow Scale Operation
in a Closed Loop Blending Control System...
Start Up
1) Turn on ay machinery used to carry the discharge material from the Flow Scale that may affect the scale Rate reading when no material is flowing.
2) Wait for scale to settle out.
3) Zero Flow Rate (F1)
4) Zero Total (F2) if necessary.
5) Make sure Controller is set to the right speed to so the Conveying Device does don’t Over Feed the Flow Scale.
6) Turn on the Scale Feed Conveying device.
7) Adjust Controller Set Speed to proper Flow Scale Rate
8) Place in Automatic Control
During Operation –Spot check
1) Count bags, bin levels incoming and outgoing truck loads, etc. and compare with Flow Scale Totalizer
2) Compare the flow scale volumetric feeder (vane feeder, auger, belt feeder, valve position, etc.) speeds with the flow scale rate. A Flow Scale accuracy problem may be occurring when they are not running in a fixed proportion to each other.
Shut Down
1) Turn off the Scale Feed Conveying device.
2) Wait for Scale Rate to return to near Zero TPH or Lbs/Min, etc. If the Scale Rate does not return to reasonably close to Zero, an accuracy problem exists. Get it fixed.
4) Turn on ay machinery used to carry the discharge material from the Flow Scale.
5) Check material used against the flow scale totalizer.
Flow Scale Integrator… F1 Zeroes the Rate
F2 Zeroes the Total. DSP toggles the
Display between Rate (TPH or Lbs/Min)
And Total (Tons or Pounds)
Display Readout (Integrator) Placement
This Device is used to read the flow rate and the total weight. The readings on this device are regularly and sometimes often (the rate reading at least daily) Zeroed by pressing the F1. This device must be located where the operator has easy access to the observe readings regularly and the manipulate keys. Locate within reach of telephone for factory support.
Load Cell Shipping/Receiving Procedure
Shipping
To Secure Load Cells for shipping, the overload screw on the bottom side of each load cell will be turned clockwise until the load cell has 0.0 mV DC Output.
Disconnect the sig+ and sig- wires from both load cell terminals and connect alligator clips from your meter, reading mV DC, to one of the load cells. Wire in the indicator and power up.
With just the weight of the basket, the 5kg load cell had a 3.8mV DC output.
Adjust the overload screw to the corresponding load cell until the output is 0.0 mV DC. Move your alligator clips to the other load cell and repeat.
Once both load cells are about 0.0, place a tie wrap through the 2 holes below the weigh basket arm and secure. Place a small piece of carboard between the tie wrap and weigh basket arm to make sure the tie wrap isn’t cut by the weigh basket arm. The model pictured has a hole on either side below the weigh basket arm. Some models have a hole directly underneath the weigh basket arm. In this case, use a piece of metal under the scale flange to secure tie wrap through one hole directly below weigh basket arm. Keep an eye on the meter and make sure not to use excessive force. The output will change after tightening the tie wrap.
Make a final adjustment to the overload screw so both load cells are reading near 0.0 mV DC output. Install load cell covers, replace sig + and sig – wires to their respective terminals, and replace j-box cover.
Receiving
Remove load cell covers and cut the tie wraps off the weigh basket arms.
With the indicator wired in and powered up, adjust the overload screw counterclockwise until a 12-mil feeler gauge will slide under the overload screw with no resistance, while a 14-mil should feel some resistance. It can be difficult to tell if the feeler gauge is contacting the overload screw or rough paint underneath. Watching your indicator reading will make it easy. If the overload screw is contacted, the reading will go slightly negative on your indicator.
Flow Scale Placement
Mount as horizontal as possible.
Material should be entering as perpendicular to the scale as possible. If it must enter at an angle, it should be flowing toward the long side of the triangles.
Scale Positioning on Horizontal Plane.. Important when feed is not falling vertically through scale.
If the flow is angled toward the short side of the triangles, material may pass right by the weigh basket without being weighed.
Like any scale, excessive vibrations must be isolated. DO NOT Firmly Mount Flow scale to an agitating piece of equipment like a pug mill, mixer, screen, etc.
Scale Discharge Transition … Important: Fabricate a tapered Square to Round transition.
Scale Discharge opening is usually 11.5” square. The product is evacuated from the scale between the diverter triangle bars. Especially with sticky or chunky product, the product flow through this area must be clear of any restrictions...
Regarding drawing below. : Scale Discharge Transition too small and restrictive… Solution.
- A) When discharging material from the flow scale into a round pipe; The Immediate (Bad) Transition illustrates a discharge too restrictive. The Gradual discharge is recommended and can be purchased as an option.
i.e. When manufacturing a square ID to round pipe transition, a round pipe has been flanged to the bottom of the 8” square Scale Discharge. The round pipe has cut the corners on the square discharge and restricted flow. Important: Fabricate a tapered Square to Round transition
- B) When discharging into an open area when flow scale discharge is sitting on a plate; situate the flow scale over a square hole the same size as the inside diameter of the scale discharge. See illustration below.
Good
Insufficient Conveyor Discharge Capacity…The Flow Rate of the Discharge Auger or Vane Feeder must always be greater than the charging rate of the Flow Scale. Sudden surges of material shall flood the flow scale and cause inaccurate readings of the scale. Significant flooding of material may lift the weigh basket and cause damage to the load cells.
Make sure the Discharge Device can always carry the flow of material away from the scale. Any surges feeding the scale may not evacuate the material being discharged fast enough which causes the scale to read light.
When capacity of scale is not keeping up with the production flow rate…
When the scale is too resistant to the required flow...
The product is backing up into the system….
Maximum Flow Rate Observation and Adjustment to increase Flow Rate.
The scale is going to present some resistant to flow and may slow the process down more than acceptable. It is difficult to determine the flow rate because of variables like materials, moistures and other varying flow characteristics .
Reducing flow restriction on the 11.5 sq is possible by eliminating some bars. Accuracy may be negatively influenced.
Check to see if scale max flow rate meets requirement for max process flow of application.
- with all bars in... discharge material though flow scale for a measured time into a container ... weigh the container... calculate flow rate ...
- document time that a) the material was allowed to flow through the scale as well b) how long it took to fill the container ... If the b) container fill time is significantly longer (assuming there was no restriction down stream of scale to container) than a) scale feed time, then a head of material is developing above the scale ... In this situation, some Diverter bars and the Bar Support part of the Grid will need to be removed from Top Grid Plate and the Weigh Basket Grid.
Removing some bars may or may not affect accuracy. Individual cases should be considered as to how much the accuracy may be affected based on best estimates. To remove the bars, the two screws are removed from the side of grid. We suggest taking out the bars as illustrated above.
Electrical
Load Cell Cover placed over Load Cell Assembly. Terminals in Summing Box with Filter Capacitor
Important: 1) Load Cell Wires Must Be Screwed Tight to Terminals at the Indicator and at Scale (notice- capacitor on terminals opposite to green and white wires-place capacitor on terminals as shown-attach load cell stranded wires to stranded wires coming from shielded cable- do not terminate solid wire of capacitor with stranded wire-). 2) Ground the shield at the Indicator Enclosure only. The bare shield wires have their own terminals. Bare wires must be taped up.
Operation... Flow Scale... … 10 volts excitation... about 2.0 mv/volt Signal...
Integrator – Rate Indicator/Totalizer
DSP button toggles display from Rate (TPH) to Totalizer (Tons)
Totalizer is 9 digit and display is 5 digit... Totals higher than 5 digits flash the indicator between the high digits (4 most significant digits MSD) and the low digits (5 least significant digits).
E.g. h9999 flash to 99.999 = 999,999.999 tons
Daily Operation... 1) Zero Rate and Totalizer with empty Discharge Augers, Blowers running, etc..2) Make sure Feed Auger, Vane, etc. is set to proper speed.
3) Make sure flow scale is reading in proportion to what the speed is reading on Feed Auger, vane, etc. 4) When through weighing, with empty Discharge Augers, Blowers, etc running; make sure Scale Rate returns to Zero. 5) Spot check flow scale with amount used.
Keys -Purpose
DSP toggles the Display between TPH Ton-Per-Hour rate and Tons Totalizer.
When TOT disappears... Display reads Rate... TPH, Lbs./Minute, etc.
PAR steps the integrator through set up and calibration program.
F1, when pressed for 3 seconds, zeros the flow scale Rate indication.
F2, when pressed for 3 seconds, zeros the flow scale Tons totalizer.
Daily Cal… Flow Scale Calibration-before startup
*Zero the Scale Rate (TPH) Indication … no material flowing before startup... press F1 for 3 secs
*Zero the Scale Totalizer (Tons)... anytime when desired...press F2 for 3 secs
*Make sure the Scale Rate returns to zero when stopping the process... if not see troubleshooting...
Factory Set Program... Operator may adjust dSP 2 only…
1 INP | 2 FNC | 3 LOC | 4 SEC | 5 tot | 6 SPt | 7SrL | 8 Out | 9 FCS |
rANGE | Usr-1 | HI | HI-t | dECPt | tYPE | d-Leu | ||
0.02v | rtot1 | LoC | O.O | O.OOO | 4-20 | 15 | ||
dECPt | Usr-2 | LO | LO-t | tBASE | ASIN | codE | ||
O.OOO | reL | LoC | O.O | hr | INP | 1 | ||
round | Usr-3 | tOt | dSP-t | SCFAC | AN-LO | |||
.1OO | no | rEd | 2 | 1.000 | O.0 | |||
FiLtr | F1 | At-t | Locut | AN-HI | ||||
25.O | no | .O | 0.4 | 50.0 | ||||
bAND | F2 | At-b | P-UP | udt | ||||
O.O1O | no | .OO2 | NO | |||||
PtS | rST | b-Lit | ||||||
2 | no | OFF | ||||||
StyLe | Sc-F1 | OFFSt | ||||||
Key | reL | O.OOO | ||||||
INP 1 | Sc-F2 | CodE | ||||||
2.OO | r-tot | 1 | ||||||
dSP 1 | ||||||||
O.OOO | ||||||||
INP 2 | ||||||||
3.OO | ||||||||
dSP 2 | ||||||||
6.500 | ||||||||
KEYSTROKES to change Span
PAR -once
Up Arrow until 1-INP
PAR until dSP 2 (11 pushes of PAR) and enter New Span with Up-Down arrows
PAR until End
Material Calibration
Plan a method to perform a material calibration by:
1-allowing material sample to flow through the scale at Average Production Rates (TPH),
2-documenting the Scale Totalizer Weight,
3-capturing the sample in a container,
4 - comparing the Flow Scale Totalization Reading with the contained sample on another verifiably accurate scale,
5 – Then adjusting the Span reading of the Dust Flo Scale Integrator.
6- Ensure acceptable scale repeatability by running another Material Test.
If Production Rates vary more than 20% plus or minus from the Average Rate calibrated for; consider performing a Multi-Point Calibration instead of only a 2 point Zero and Span Calibration
A Calibration Discharge Gate may be necessary after the Flo Scale to capture the sample; otherwise measure the amount going into the flow scale.
Calibration Methods
- Some applications may favor a slide jam gate welded to the underside of an auger downstream of the flow scale.
- Other applications may favor Calibration Discharge Diverter Tube. The flow scale sits on the Diverter Tube and adds 2 to 3 feet in height to the flow scale. A plate is taken off the Diverted Discharge Port and a Diverter Plate is slid into position and bolted down.
- Place a known weight in surge/silo, run the material through and make appropriate span corrections.
Material Calibration-installation, plant calibration, accuracy confirmation and troubleshooting
*Zero the Scale Rate (TPH) Indication … no material flowing... press F1 for 3 secs
*Zero the Scale Totalizer (Tons). press F2 for 3 secs
*Immediately run material through at the rate (TPH) you plan on producing at.
*Document Total immediately (wait for Rate to slowly work down to 0 TPH or Lbs/Minute) after material flow is no longer being measured.
* Compare scale weight with flow scale totalizer weight. If correction is needed, adjust Flow Scale Span calibration by Formula below.
- Calibration Scale /Flow Scale X (DSP 2 Value) = New Span DSP 2 Value
- Press PAR Button (Program mode), then F1 until, then PAR then ‘dSP2 Value’ and update with New Span Value.
- Press PAR until out of the Program mode and into the Run mode
KEYSTROKES to change Span
PAR -once
Up Arrow until 1-INP
PAR until dSP 2 (press PAR 11 Times) and enter New Span with Up-Down arrows
PAR until End
Material Calibration:
Flow Scale is to measure the flow of material as passed through the flow scale and counted on the totalizer and compared with an independent scale reading. Verification.
Verification Scales...
Scales may be Optional EZ-Flo Material Calibration Scale (Verification Scale) with remote Digital Indicator and 55-gallon drum
EZ-Flo Flow Scale Calibration Data Sheet (Material Calibration)
Note - Maximum 400 lbs when using the EZ- Flow Calibration Scale
Average Operating Flow Rate _____TPH (Run Test at this flow rate) Date______
Re –Weigh Drum for new Tare after every Test. Check to See that The Scale Flow Rate returns to Zero TPH after every use (Material Calibration or Production).
Time | Rate
TPH Lbs/m |
Flow Scale Tons | Flow Scale Lbs | Calib Scale Gross | Calib
Drum Tare |
Calib Scale Net | Cal Scale/ Flow Scale Lbs Ratio | DSP Multiplier | Exist-ing
DSP 2 |
New DSP 2 |
Trouble Shooting
Trouble Shooting Aids
- Most Necessary Aid… Telephone in reach of Scale Integrator
- mv DC meter reading in tenths of millivolt
Symptoms.
Problems... Corrections.
Zero wanders when no machinery is running.
Load Cell Electro-Mechanical Connections... Ensure that Load cell wires are screwed tightly to terminals. Make sure Load Cell and Weigh Basket Bracket are securely tightened together with spherical washers above and below weigh basket bracket.
Load cell cable shield has been grounded at both ends... disconnect ground at scale. Make sure bare shield wires are taped.
Flow Rate deviates above and/or below after being Zero when machinery is running.
Excessive Change in Vibration…decrease vibration and vibration changes
Excessive Air Flows or changes in air flows... decrease or eliminate air flows
Flow Rate Zero not properly Zeroed… Before weighing material, allow scale to settle out before Pressing F1. Example: If Scale is zeroed and then scale settles to 2 tph above zero and then the weighing process begins and the scale reads 20tph; the flow rate reads 20 tph while only 18 tph is being added. Important: Startup all the machinery (fans, conveyors, etc.) for the process except the device feeding the scale, then zero out the rate. This is more like the condition the scale has to work while in the process. FYI. Variable speed scavenge fan air flow can make for random inaccuracies if there is air flowing through scale.
Load Cell Electro-Mechanical Connections... Ensure that Load cell wires are screwed tightly to terminals. Make sure Load Cell and Weigh Basket Bracket are securely tightened together with spherical washers above and below weigh basket bracket.
Bad Load Cell… Check Load Cell. Check the mvdc reading on both load cells (Signal terminals in Summing Box) when no material is flowing through and no material on the weigh basket. This will be the MV DC Tare signal when material is not flowing through. The load cell should return to near the same reading when not under load. If they do not, you may either have 1) a buildup of material on or around the weigh basket or load cell or 2) a bad load cell. Load Cell readings should be within .5 MV from each other.
Rate Indication does not increase with increased flow rate.
Check for proper load cell flexing clearance ..
Each load cell has an overload screw on the bottom side. A washer is used as a shim between the load cell and the scale body on both mounting bolts. This provides enough space to get a wrench under the load cell to adjust the overload screw, as well as compensates for any inconsistencies in the mounting platform, such as powder coat paint thickness, bent flange during shipping, etc. A feeler gauge will be used to set the overload screw.
A 12-mil feeler gauge should slide under the overload screw with no resistance, while a 14-mil should feel some resistance. Regarding the overload screw or any part of the load cell base extending from the two mounting bolts and washers underneath is contacting the scale body under the load cell, it will be underloaded and give an inaccurate light Rate Reading.
The magnitude of the lighter weigh error depends on how much load cell load causes the load cell base to contact it’s mounting flange. An under loaded load cell can be identified by physically seeing the overload screw or load cell contacting the flow scale body under the load cell; or by checking the mvdc reading on both load cells. The load cells should have a similar readings and not be negative.
If one is considerably different from the other, then check the load cells to make sure one or other or both are not overloaded by sliding a feeler gauge underneath while observing the mvdc readings. If the mvdc output is decrementing, then your load cell is overloaded. Either adjust the overload screw up so that it doesn’t touch the scale body or add another set of washers under the load cell to keep the load cell from touching scale body (if you add washers under one load cell you must add washers under the other load cell to keep them on the same plane). If neither of the load cells are overloaded and the readings are considerably different, you may have a bad load cell. Load Cell readings should be within .5 MV from each other.
Zero Rate oscillates excessively fast around zero making it difficult to read and to zero the rate.
Filter Setting…Increase filter setting on integrator and/or insure Filter Capacitor on Load Cell Signal Wires are tight and/or increase the size of the Load Cell Filter Capacitor.
Observing the Scale Readings, after weighing material with all process machinery still on except scale feeder it is noticed the Rate Indicator has not returned near zero.
Excessive Vibration… decrease vibration
Excessive Change in Vibration…decrease vibration and vibration changes
Excessive Air Flows or changes in air flows... decrease or eliminate air flows
Flow Rate Zero Procedure not properly Zeroed… Before weighing material, allow scale to settle out before Pressing F1. If Scale is zeroed and then scale settles to 2 tph above zero and then the weighing process begins and the scale reads 20tph; the flow rate reads 20 tph while only 18 tph is being added.
Rate Indicator weighs light.
Weigh Basket Bracket Contacting Flow Scale Wall... Weigh Basket Bracket Mechanically passes the force applied to the Weigh Basket from the product flow to the load cell. The Weigh Basket Bracket passes through a slot in the wall of the Scale Body. Insure the Weigh Basket Bracket is not rubbing against the edge of the slot.
Material Calibration Tests are excessively unlinear.
Regarding Weigh Basket to the two Load Cell misalignment; the Spherical Washer set between the Load Cell and the Weigh Basket Bracket is used to eliminate the mechanical stresses. As you can see in the left picture below, the concave washer is offset from the convex washer. This allows the basket to be attached firmly to the load cells without causing mechanical stress from a weigh basket assembly completely aligned to the load cell plane.
Product building up under weigh basket bracket...This may impede movement of weigh basket causing inaccurate readings. a) consider connecting a dry air source at 8 psi to the tubes that are run behind the load cells.
Regular Maintenance. The Load Cell cover below allows one to check for material buildup under the weigh basket bracket. The cover should be taken off to inspect no buildup under the load cell.
FYI.. The silver cover in the middle of scale covers the Load Cell Summing Box.
Rate Indicator Weighs Light and later Heavy
Product Buildup on Weigh Basket. Sticky material does not work with this scale. May be caused by sticky product or excessive moisture, etc in the product causing it to be sticky. As product starts to stick to the weigh basket, the zero will progressively go up. You may have a positive TPH reading when stopped. This can indicate product buildup on the weigh basket. You may later have a negative TPH reading when stopped. This can indicate that a buildup of material on the weigh basket has fallen off .
Possible cures may be to check and fix any air dryer problems for the silo cone air pad for air fluidizing the product (refrigerated air dryer or desiccant dryer) or safely manually cleaning the weigh basket when the process has stopped.
Zero reading moving excessively.
Load Cell Electro-Mechanical Connections... Ensure that Load cell wires are screwed tightly to terminals. Make sure Load Cell and Weigh Basket Bracket are securely tightened together with spherical washers above and below weigh basket bracket.
Bad Load Cell… Check Load Cell.
Product Flow Backing up into Scale…Scale not evacuating Product as quickly as it is being weighed. This is many times caused by Scale Discharge Feeder being overwhelmed with too much flow or Scale Discharge Feeder running to slow or Product too sticky or moist or Scale Discharge Transition too small and restrictive.
Load Cell Mechanical Connections are loose.
Flow Scale Accuracy not as expected.
Material Dependant … is make up of material changing flowability, such as changes in moisture, temperature, density...
Installation Dependent... changes in vibration... erratic air flows...extreme temperature changes
Application Dependent... significant changes in flow without calibrating at significantly different flow ranges.
Air Current through scale body causing flow of air to negatively or positively influence the force that the weigh basket places on the Load Cell. Seal up covers on scale and use air locks when necessary.
Calibration Sample Size Dependent... too small of sample to adequately represent accuracy required. Adjust DSP 2 to long term known weight usage.
During Material Calibration…. Inconsistent clearing out scale discharge procedure (augers, etc) during Material Calibration .i. e. Discharging product from Scale discharge auger for 3 minutes sometimes and only one minute other times causes this problem. When material is stopped at the feed end of the scale and the amount of time the discharge auger feeding the Material Calibration Container is stopped varies, so will the amount of material being fed to the Calibration container. Set a fixed time from test to test. When the discharge auger is allowed to run longer than the test before, the discharge auger cleans more material out of auger into the Calibration Container than before without the scale accounting for it.
Weigh Basket Build Up Dependant… mid-stream rezero or manually clean weigh basket.
Load Cell Electro-Mechanical Connections... Ensure that Load cell wires are screwed tightly to terminals. Make sure Load Cell and Weigh Basket Bracket are securely tightened together with spherical washers above and below the weigh basket bracket.
Material Buildup around base of load cell.
The Weigh Basket Bracket passes through a slot in the flow Scale Body. Small amounts of Weighed Material Dust may pass through behind the load cell cover and buildup over time.
This must be checked regularly and cleaned away when necessary. The build up of material may impede the slight travel of the weigh basket bracket. ¼” tubing is placed behind each load cell. 8 PSI dry air should be connected to help keep product from building up around the load cells and weigh basket brackets.