Suunto DX User Guide
Alarms, warnings and notifications
Suunto DX has audible and visual alarms designed to let you know when important limits or presets are being reached.
The two audible alarm types indicating high or low priority:
| Alarm type | Sound pattern | Duration |
|---|---|---|
| High priority |  | 2.4 s sound + 2.4 s break |
| Low priority |  | 0.8 s sound + 3.2 s break |
In addition, there are three audible guidance notifications:
| Instructional beep | Sound pattern | Interpretation |
|---|---|---|
| Ascending |  | Start ascending |
| Descending |  | Start descending |
| Descending-ascending |  | Change gas |
Suunto DX displays information during the alarm breaks in order to save battery life.
High priority alarms:
| Alarm | Explanation |
|---|---|
High priority alarm followed by 'Start ascending' beep, repeated for maximum three minutes PO2 value blinks | PO2 value greater than the adjusted value. Current depth is too deep for the gas in use. You should immediately ascend or change to a lower O2% gas. |
High priority alarm followed by 'Change gas' beep, sounded two times. PO2 value blinks | PO2 value is smaller than 0.18 bar (Mixed or CCR mode only). The depth is too shallow and the ambient pressure is too low for the current gas. The oxygen content is too low; you may lose conscious. You should immediately switch the gas. |
| High priority alarm followed by 'Start descending' beep, repeated for maximum three minutes Er blinks and an arrow points downwards. | Decompression ceiling depth exceeded. You should immediately descend to, or below, the ceiling. |
High priority alarm, repeated three times. SLOW blinks. | Maximum ascent rate of 10 m/min (33 ft/min) exceeded. Slow down your ascent rate. |
Low priority alarms:
| Alarm type | Alarm reason |
|---|---|
Low priority alarm followed by 'Start ascending' beep, sounded two times. ASC TIME blinks and an arrow points upwards. | No-decompression dive becomes a decompression stop dive. Depth is below the decompression floor level. You should ascend to, or above, the floor. |
| Low priority alarm followed by Change gas' beep. The gas mix percentage value blinks. | Gas change is recommended (Mixed or CCR mode only). You should change to a gas more favorable to decompression. Ascent time calculation assumes that the gas is changed and is therefore only accurate if you have changed the gas accordingly. |
| Low priority alarm followed by “Change gas” beep, sounded once. The backlight is lit and text "Set Point selected is displayed shortly. | The setpoint has been switched automatically upon reaching the defined depth (CCR mode only). |
Low priority alarm followed by 'Start descending' beep. DEEPSTOP blinks and an arrow points downwards. | Mandatory deepstop violated. You should descend to complete the deepstop. |
Low priority alarm followed by 'Start descending' beep, repeated for three minutes. An arrow points downwards. | Mandatory safety stop violated. You should descend to complete the safety stop. |
Low priority alarm followed by two short beeps. DEEPSTOP and timer displayed. | Deepstop depth reached. Make the mandatory deepstop for the duration shown by the timer. |
Low priority alarm, repeated twice. Tank pressure value blinks. | Tank pressure reaches the defined alarm pressure or the fixed alarm pressure, 50 bar (700 psi). Acknowledge the alarm by pressing any button. |
Low priority alarm, repeated twice. OLF% value blinks if PO2 value is greater than 0.5 bar. | OLF value at 80% or 100% (Mixed or CCR mode only). Acknowledge the alarm by pressing any button. |
Low priority alarm, repeated twice. Maximum depth value blinks | Defined maximum depth or the maximum depth of the device exceeded. Acknowledge the alarm by pressing any button. |
| Low priority alarm, repeated twice; dive time value blinks | Defined dive time exceeded. Acknowledge the alarm by pressing any button. |
Visual alarms
| Symbol on display | Indication |
|---|---|
 | Attention - extend surface interval |
| Er | Violated decompression ceiling or bottom time is too long |
 | Do not fly |