# A18 Low Flow Cutoff

### Definition

This function forces the flowmeter to display flow values below a set threshold as **0**. The default value is **0**, which disables the function.

When **A18 Low Flow Cutoff** is disabled, small near-zero measurement fluctuations may be displayed, causing slight value variations when the system is stopped.

To display a stable **zero flow** when the system is stopped, enable **A18** to force flow values below the threshold to zero, preventing zero drift and minor measurement disturbances.

### Notes

1. The default value is **0**, which means the function is disabled and the flowmeter will display actual small flow values.
2. The condition **“below the set value”** is evaluated using the **absolute value** of the flow rate. Regardless of forward or reverse flow, any value lower than the set threshold will be displayed as **0**.
3. **A18 is a hard cutoff for both display and output.** When the actual flow rate is lower than the A18 setting, the flowmeter will display **0** and no flow variation within this range will be output.
4. If the application requires measurement of small flow fluctuations near zero, the measured flow value **must be greater than the A18 setting**. Otherwise, the flow will be treated as **0** and cannot be measured or recorded.
5. **Setting Recommendations**
   * **General process display / PLC false-trigger prevention:**\
     Set **A18** close to the lower measurement limit of the flowmeter model to improve zero stability.
   * **Low-flow detection / micro-flow research applications:**\
     It is recommended to disable **A18 (A18 = 0)** to preserve full measurement information near zero flow.

**\******Lower measurement limit***

<table><thead><tr><th width="106.7109375"></th><th></th><th></th><th></th><th></th><th></th></tr></thead><tbody><tr><td>DN</td><td>DN8</td><td>DN10</td><td>DN15</td><td>DN20</td><td>DN25</td></tr><tr><td>Lower measurement limit</td><td>1 LPM</td><td>1 LPM</td><td>2.5 LPM</td><td>2.5 LPM</td><td>5 LPM</td></tr></tbody></table>

### Operation Procedure

<details>

<summary><strong>Button Functions</strong> <em>(Click to Expand)</em></summary>

The main unit has **four buttons**. The **bottom line (Line 3)** of the LCD displays the current function of each button. Under normal operation, the button functions are as follows:

* <img src="/files/bdd75120acea6361d128fd3deec06f1a8277e667" alt="" data-size="line"> **Blue Button -** Leftmost button: Return, exit, or save settings.

Gray Arrow Buttons:

* <img src="/files/2e37e572251371c6020ab6d9e11c1fcdd5ef0369" alt="" data-size="line"> **Left Gray Button:** Previous Page, decrease value, or select item
* <img src="/files/50a67ff5744401e217d5b9e838da3f7909be732f" alt="" data-size="line"> **Right Gray Button:** Next Page, increase value, or select item
* <img src="/files/6c0b22a2048cf9b2afd86fac7a65e414feb967d4" alt="" data-size="line"> **Orange Button:** Rightmost button: Enter settings, edit, or confirm selection

{% hint style="danger" %}
**Do not hold buttons for extended periods to avoid damage.**
{% endhint %}

{% hint style="info" %}
Button functions may change depending on the operation context to improve usability or prevent accidental presses.
{% endhint %}

</details>

```
A18 Low flow cutoff Setting Steps
• From the main screen(green backlight), 
press Orange Button(Setup) to enter settings (orange backlight).
• Use Gray Arrow Buttons to select A. Measurement, press Orange Button(Enter).
• Use Gray Arrow Buttons to select A18 Low flow cutoff, press Orange Button(Enter).
• Use Gray Arrow Buttons to choose the digit to adjust(highlighted in dark gray).
• Press Orange Button(Edit) to enter adjustment mode.
• Adjust digits: Left Gray Button to increase, Right Gray Button to decrease.
• Press Orange Button(Set) to confirm each digit; repeat for other digits as needed.
• After all digits are set, press Blue Button(Save).
Confirm by pressing Orange Button(Save) (or Blue Button(NOT) to cancel).
• Press Blue Button(ESC) to return to the main screen(green backlight).
```

<figure><img src="/files/9EOqvE3i7UNYi3h0NIQg" alt="" width="375"><figcaption></figcaption></figure>

### A18 Options, RS485 Values, Read/Write Commands, and Formats

| Input Range of This Parameter | Corresponding Values | RS-485 Value |
| ----------------------------- | -------------------- | ------------ |
| Custom                        | 0                    | -            |
| Minumum                       | 0                    | -            |
| Maximum                       | 150,000,000          | -            |

> Refer to the[ Read/Write Memory List](/qr/fu-lt-english-v1/communication/modbus-rtu-protocol/read-write-memory-ram.md) for the Modbus command format. This parameter uses the float 32 data format.


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