Figure 8 is the old hand signal for fire. Problem is that some marshallers couldn't count that high and made confusing motions that a pilot might mistake for a movement signal.
Now it's a sweeping motion with one hand below the waist.
There isn't any specific universal signal for pressurization or depressurization of hydraulics any more because nobody at the ATA conferences can agree on anything.
General rule is that if the sign is being made below the belt level it's an abnormal, non-movement, or emergency sign and signs above the waist are normal movement signals.
My personal opinion - it's long past time to get one set of standarized signs like we had pre-1985. The current "system" of whatever the marshaller feels appropriate is woefully inadequate and often borders on dangerous.
