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Those often have a Mute button!! It's always unlabeled, but the upper-right (or second-down-from-upper-right) button is usually Mute. If not those, then one of

Those often have a Mute button!! It's always unlabeled, but the upper-right (or second-down-from-upper-right) button is usually Mute. If not those, then one of the others probably is. If you have a sharpie on you, label it for the next poor soul that has to use that pump.

RunSet 4y ago
If they don't have a mute button you can implement the functionality by using ordinary chewing gum to block the speakers.