# A22 Auto Zero Offset

### Definition

Recalibrates the flowmeter zero point, resetting the output to zero. Recommended for ultra-low flow measurement to correct zero-flow offset errors and improve measurement accuracy. 

Starts only after pressing **Start** and automatically updates the **Z04 (Auto Zero Flow)** settings.

It is recommended to perform **Z04** when measuring ultra-low flow (below 10% of the maximum range), as small zero-point offsets can cause significant errors at low flow.

**Example:** With a zero-point offset of 0.2 L/min:

* At an actual flow of 100 L/min, the error is approximately 0.2%.
* At an actual flow of 0.5 L/min, the error can reach nearly 40%.

{% hint style="info" %}
Currently, **A22** does not support Modbus read/write command operation.
{% endhint %}

### Notes

1. Perform **A22**  when the pipeline is <mark style="color:red;">**fully filled with liquid and the liquid is completely stationary**</mark><mark style="color:red;">.</mark> Performing Z04 when the pipe is not full may cause flow measurement errors and unstable readings; if this occurs, repeat Z04 under full-pipe conditions.
2. <mark style="color:red;">**Repeat this procedure after every reinstallation or when changing pipe size or material.**</mark>
3. The **A22** function is equivalent to **Z04**; users can choose either.\
   (Z-series parameters are designed for quick setup, consolidating multiple essential settings to streamline installation.)

### 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>

```
A22 Automatic Zero Offset Setting Steps
• From the main screen (green backlight), 
press Orange Button (Setup) to enter settings (orange backlight).
• Use Gray Arrow Buttons to select  Z. Easy Setup , press Orange Button (Enter).
• Use Gray Arrow Buttons to start Automatic Zero Offset
• Device shows “Start auto Z04” when automatic zero-flow begins.
• After ~30 seconds, it displays “Set zero offset to ____”.
• Then it returns to Z04 Auto Zero Flow, indicating completion.
```

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


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