Question 1

1. How do I know if my medium is conductive enough?

Accepted Answer

All magmeters require a minimum medium conductivity for the technology to measure flow. Medium conductivity of at least 20 µS/cm is required for the SM family. The chart provides general guidelines on conductivity of common media.

Question 2

2. If the conductivity of my liquid changes, will the SM magmeter be affected?

Accepted Answer

No. So long as the conductivity is at least 20 µS/cm, the magmeter will perform to specifications; higher or varying conductivity will not affect performance. Media with conductivity below the 20 µS/cm threshold produce low induction voltages, making it difficult or impossible to distinguish the difference between the signal voltages and noise voltages.

Question 3

3. What is the impact of temperature, pressure and viscosity changes of my liquid?

Accepted Answer

Negligible when within our published specifications. Higher viscosity fluids will result in a larger pressure drop through the meter and a minor impact on accuracy. Medium temperature can be higher than specified when the ambient temperature is relatively low.

Question 4

4. Are versions available with analog voltage output?

Accepted Answer

Yes. Click here for a list of these units.

Question 5

5. How do deposits on the measuring electrodes affect the meter?

Accepted Answer

Generally, magmeters are known to be low-maintenance. However, if the water quality is such that build-up of solids or other materials stick to the measuring electrodes, there will be a decrease in the signal until the build-up is removed. This can be done using a soft brush and an appropriate dilute cleaning solution.

Question 6

6. Where are the electrodes located?

Accepted Answer

For the meters with 10-segment LED display, the electrodes are visible when looking through the measuring tube. For the meters with TFT display, the electrodes are not visible. With the display on top, the electrodes are on the sides of the measuring tube, rotated +90 ° and -90 ° from the display. This can be important when the need for cleaning the electrodes arises or in situations where orientation affects the function, such as a partially filled pipe.

Question 7

7. What happens with bubbles in the medium?

Accepted Answer

Uncovered electrodes, due to air bubbles or because the pipe is not full will cause measuring errors. Larger magmeters (SM2xxx and SM9xxx) have built in empty pipe detection and can provide a stable “0” signal in these cases.

Question 8

8. Must I do anything special to install the magmeter in a plastic pipe?

Accepted Answer

Because of the minimum measuring voltage required, stray grounding or noise current can cause errors. Make sure the meter is properly earth grounded. E40234 grounding clamp can be attached to the electrical connector and a ground wire can be run to earth ground.

Question 9

9. What are the internal dimensions of the measuring tube?

Accepted Answer

For the units with 4-digit LED display, the measuring tube is tapered to get the most reliable signal, even with low flow velocities. Because the lining of the flow tube is PEEK, there is minimal pressure drop through this orifice. Refer to the pressure drop curve on the product datasheet.

SM4 = 2 x 5 mm
SM6 = 4 x 8 mm
SM7/8 = 8 x 12 mm
SM9/2 = 17.5 x 36 mm

For units with multicolor TFT display, the measuring tube is round.

SM6x2x = 8 mm
SM7x2x = 12 mm
SM8x2x = 16 mm

Question 10

10. How do I calculate the accuracy of the SM meters?

Accepted Answer

Most of ifm’s flow meters use a two-part accuracy calculation, based on the measuring range (MW) and full range of the meter (MEW). For example, accuracy of the SM2001 (MEW = 160 gpm) is specified as:
± (0.8% MW + 0.5% MEW)
For MW = 100 gpm, accuracy = ± (0.008*100 + 0.005*160) = 1.6 gpm

Consult each product's datasheet for the actual accuracy specification.

Question 11

11. What is the accuracy of the totalizer feature in the SM magmeters?

Accepted Answer

We do not specify the accuracy in our datasheet, but testing has shown accuracy in the 0.5% - 0.7% range.

Question 12

12. What is the difference between pulse output and frequency output?

Accepted Answer

The SM magmeters have a pulse output that is used for dosing or totalizing applications. A 24 VDC signal is sent every time a specified volume (e.g., 0.1 gallons, 1 ml, etc. entered as ImPS in the menu) flows through the meter regardless of the flow rate. When the parameter FPro is set to "0+", pulses are only counted when flow is in the postitive direction indicated by the arrow on the body of the sensor. When FPro is set to "-+", pulses are generated when flow is in the postitive direction, however, any flow in the negative direction is subtracted from the total volume and must be replaced by positive flow before pulses are generated again.

The SM meters also have frequency outputs, which provides a digital signal directly relatable to the flow rate. This digital signal can be further evaluated with counters, PLCs, etc. Frequency outputs are often used for mechanical flow meters like turbine meters. The rotational motion of the turbine, which turns according to the flow rate, is detected and converted into frequency signal. If the flow is reversed, frequency signals stop. Once the flow rate returns to the positive direction, the frequency signals will return at the correct rate.

Question 13

13. What is the ZH4217 and how do I use it or another external pushbutton to reset the totalizer?

Accepted Answer

The ZH4217 is a kit consisting of KT6301 pushbutton, E12380 cover for the pushbutton labeled "OFF", and EVC847 y-splitter.

Setup

On the SM, change OU2 to [In.D] and Din2 to [HIGH] using the step-by-step procedures below. These procedures should be used with any external pushbutton reset.
When using the ZH4217, connect the KT6301 to channel B of the EVC847 and connect the SM sensor to channel A. Then, connect power to channel C with pin 1 to +24 VDC and pin 3 to ground.

The totalizer will be reset to zero when the pushbutton is pressed.

For 3-pushbutton SMs

Press Mode / Enter button to enter menu.
Press [▼] to OU2, press mode enter button.
Press and hold [▲] or [▼], the display will begin to flash. Keep [▲] or [▼] pressed until [In.D] is displayed. Release and briefly press mode enter. (OU2 will be displayed)
Press [▼] until DIn2 is displayed. Briefly press mode enter.
Press and hold [▲] or [▼], the display will begin to flash. keep [▲] or [▼] pressed until [HIGH] is displayed. Release and briefly press mode enter.

For 2-pushbutton SMs

Press Mode / Enter button to enter menu.
Press Mode / Enter button to OU2, press set button.
Press and hold set button the display will begin to flash. Keep Set button pressed until [In.D] is displayed. Release and briefly press Mode / Enter. (OU2 will be displayed)
Press Mode / Enter button until DIn2 is displayed. Briefly press Set button.
Press and hold Set button; the display will begin to flash. Keep Set button pressed until [HIGH] is displayed. Release and briefly press Mode / Enter.

Magmeters: Troubleshooting and frequently-asked-questions

FAQs