Frequently Asked Questions

Q1:  How much power does the WaterFeature8 consume?

Q2:  At what ambient temperatures will the WaterFeature8 reliably operate?

Q3:  What are the display ranges of the LCD HMI?

Q4:  What are the analog output ranges of the WaterFeature8 board?

Q5:  How do I calibrate sensors?

Q6:  How do I calibrate a flow meter?

Q1:  How much power does the WaterFeature8 consume?

A1:  The WaterFeature8 is designed to nominally operate on +24 VDC power.  The maximum power consumption at +24 VDC is about 0.5 W (0.02 A).

The WaterFeature8 will also run on less than +24 VDC, and has been succesfully powered with +12 VDC.  However, at +12 VDC the analog output signals may perform erratically, particularly at long current loop wiring runs.

Voltages above +24 VDC nominal will cause damage to the WaterFeature8 board, at may potentially damage attached sensors and EZO circuits.

Q2:  At what ambient temperatures will the WaterFeature8 reliably operate?

A2:  In general, the limiting temperature component is the 4x40 character LCD HMI screen.

     Minimum Temperature = -20C (-4F)

     Maximum Temperature = 60C (140F)


Note that the LCD module will appear sluggish at low temperatures which may obscure the display quality.  However, this does not interfere with analog output performance.

Q3:  What are the display ranges of the LCD HMI?

A3:  Each EZO/sensor combination has a specific range of readings they are able to observe and display.  Note that these ranges are different from the analog output ranges due to the LCD character limitations and output circuit resolution.


Also, only four characters are dedicated to displaying the sensor value.  In most cases, if the reading is under 100, then one value after the decimal can be displayed.  If the reading is under 10, then two places after the decimal may be available.

Dissolved Oxygen [DO]

0.01 resolution (e.g. 2.05 mg/L)

Oxidation Reduction Potential [ORP]

1 resolution (e.g. 256 mV)


0.01 resolution (e.g. 9.08 S.U. for values below 10.0)

to 0.1 resolution (e.g. 11.5 S.U. for values 10.0 or higher)

Temperature [RTD]

0.1 resolution (e.g. 55.2 F)

or 1 resolution (e.g. 112 F)

Flow [FLO]

0.01 resolution (e.g. 0.86 gpm)

to 1 resolution (e.g. 421 gpm)

Electroconductivity [EC]

0.001 resolution (i.e. .526 mS/c)

to 1 resolution (e.g. 115 mS/c)

Do not confuse resolution with accuracy.  The system is only as accurate as the sensor/EZO combination.  The resolution is simply the reported value.  Refer to Atlas Scientific's website for more information regarding sensor/EZO accuracy.

Q4:  What are the analog output ranges of the WaterFeature8 board?

A4:  The WF8 uses a 16-bit signal circuit which allows for 65,536 current values between the boundaries of 4 mA and 20 mA.

Dissolved Oxygen [DO]

Low (4 mA) = 0 mg/L

High (20 mA) = 10 mg/L

Oxidation Reduction Potential [ORP]

Low (4 mA) = -1,020 mV

High (20 mA) = 1,020 mV


Low (4 mA) = 0

High (20 mA) = 14

Temperature [RTD]

Low (4 mA) = 25 F

High (20 mA) = 252 F

Flow [FLO]

Low (4 mA) = 0 gpm

High (20 mA) = 525.2 gpm

Electroconductivity [EC]

Low (4 mA) = 0 mS/cm

High (20 mA) = 200 mS/cm at 20 mA

Q5:  How do I calibrate sensors?

A5:  The WaterFeature8 includes a simple calibration submenu that is accessible from the Home Screen.  Each sensor type has slightly different calibration requirements.  Follow the on-screen prompts to calibrate each individual sensor.  Detailed instructions are included in the provided instruction manual, and can also be downloaded from our Downloads page.

Calibration information is stored in each specific EZO and is retained when power is turned off.  Calibration values are NOT overwritten when the AutoConfig feature is performed.

Q6:  How do I calibrate a flow meter?


A6:  Flow meters are not calibrated the way a DO probe or ORP sensor is calibrated.  The K-value of the meter must be manually changed in the FLO EZO to modify the volume calculated per revolution of the meter.

A meter's K-value will be set up in the FLO EZO in one of two ways:


  1. For a single K-value meter:  relating the volume per pulse to the number of pulses counted.

  2. For a multiple K-value meter:  relating the volume at different revolution speeds to the observed frequency in Hz.

The FLO EZO simply counts pulses between polling times, and "does the math" whenever we ask the circuit for a flow rate reading.  Therefore, we need to change the K-value memory of the FLO EZO circuit.  This involves performing a bucket test or similar field test to confirm the flow rate, and then reprogramming the EZO so that the K-value represents this new flow rate.

The procedure steps are:

1.  Obtain an appropriately large container depending on meter size.  Maybe a 5 gallon bucket?  Maybe a 50 gallon drum?  Maybe a 275 gallon tote?  Depends on the meter size.  Bigger meters will require larger calibration volumes.  Use good judgement here ... the exact volume size is not critically important.

2.  Measure out a KNOWN volume of liquid into the container.  For example, use five one-gallon jugs to fill a 5 gallon bucket and make a line on the container at this known liquid level.

3.  Run flow through the meter into the container, noting the observed flow rate, and timing the fill duration.

4.  Perform the relevant conversion calculations based on flow observations and time to fill (see example below).

5.  Update the FLO EZO K-values.  This requires turning off the WaterFeature8, removing the EZO from the socket, programming it manually, reinserting the EZO back on the WF8 board, and turning the system back on.  Instructions to perform this programming can be found on our Downloads page.

Flow Meter Calibration Example:


Assume this example flow meter has a single K-value of K,[0.25 gpm,5 pulses] programmed into the FLO EZO.

To establish baseline performance, we fill a 5-gallon bucket with exactly 5-gallons of water using a one-gallon jug.  We mark the water level with a permanent marker and dump the water out.

Then we run the bucket test.  The WaterFeature8 reports 0.20 gpm during the fill, and the time to fill to 5 gallons is 22 minutes.  This gives us an actual flow rate of 5 gal / 22 min = 0.227 gpm.

According to the meter (and thus the default K-value in the FLO EZO) it should have taken 25 minutes to fill the bucket (5 gal / 0.2 gpm).  However, since it actually took 22 minutes to fill the bucket, we know that the actual flow is a bit higher than the meter reading, and that the meter is under-reporting the actual flow.  Therefore, the volumetric parameter of the K-value needs to be increased so that a greater volume is reported for the same number of pulses.

The calculation involves adjusting the K-value by the ratio of the bucket test actual reading to the reported theoretical reading.  In this example the K-value needs to be shifted by [actual] / [reported] = 0.227 gpm / 0.2 gpm = 1.135.

We multiply the volume portion of the K-value by 1.135, thus 0.25 gpm x 1.135 = 0.284 gpm.

The corrected meter K-value is K,[0.284 gpm,5 pulses], and this value needs to be programmed into the FLO EZO firmware.

Refer to our Downloads page and check our our EZO programming instructions.  It is not very difficult to do, we promise.


© 2020 by Integrated Treatment Systems, LLC.