Ingersol Rand Manriding winches are equipped with extra safety feature - availability of hooking up alternative power supply to lower the Man in Manriding aloft.
Below is the extract from the Manual:
Emergency Lowering Device
This device allows the person to be lowered safely in case of air supply failure.
1. In the event of air supply failure, operate the three way valve from normal inlet air supply to the emergency inlet supply.
2. Open the emergency air supply (power) source. Ensure that downstream pressure is 73 to 102 psi (5 to 7 bar).
3. Operate the winch slowly to open the brakes and lower the person safely.Operate the winch slowly to open the brakes and lower the person safely.
WARNING
• After each use of emergency lowering device, return the three valves to the normal air inlet and check the secondary air supply (power source) is in proper working condition and able to fulfill its task.
NOTICE
• For the emergency air supply (power) source, a 50 litres nitrogen bottle can be used.
I am personally convinced that the issue with Emergency Lowering is not so critical for land rigs/hoists:
1. Manriding harnesses are designed for person to sit and work, opposite to conventional harnesses designed only to arrest fall. It is a work tool, rather than HSE tool.
2. The Manrider can stay suspended without being exposed to hazard of falling, as brakes work in such a way – if there is power – it disengages brakes and drum rotates, if no power brakes are engaged.
3. All drilling and hoisting devices MUST be shut down anyway for Manriding operation, so no risk of being hit by moving equipment. Worst case scenario – NPT.
4. Hazard of swinging and hitting something not applicable to us, as we are not like may be in the Offshore units – rolling from side to side. In case of wind Manrider can be provided with a lanyard to secure himself somewhere to prevent swinging.
5. Nevertheless, there is a risk of delayed support to the Manrider, if he is injured and we have power failure at the same time. – But how realistic this happening?