Zero-energy states

The assessor should also find out whether an effective testing program is in place to help ensure the serviceability of process measurement equipment. The successful toller should have an established calibration program to address the accuracy of critical measurement equipment. Safety critical process parameters should be monitored and critical process equipment should automatically interlock when monitoring instrumentation detects safety critical deviations. Interlocks should either facilitate a remedy to the critical deviation or bring the process to the zero energy state. These instruments and interlocking devices should be routinely tested to ensure operational reliability. 

It should be noticed that if the zero energy state of the system is arbitrarily taken as that of the liquid at the pressure, volume, and temperature p0, % T0, then the initial heat content will be Eq+PqVq, which does not vanish when Ea—0. The difference pQv0 in the case of water at 0°C. is very small, being equal to lxvap. press, at 0°/J g.cal., where / is the mechanical equivalent corresponding with the pressure unit. In practice, it is neglected. 

This difference is measurable. Changing the potential of the catalyst modifies its Fermi level, Ef, or in other terms, the electrochemical potential of the electrons in the catalyst, e ( = ) This latter is defined as the difference between the zero energy state of the electrons (taken at ground state at infinite distance from the solid) and the energy of a conduction electron in the bulk of the catalyst. It is common practice to count this energy difference in two conceptually different ways. One of them is common in electrochemistry, the other is common in surface science. 

The state in which the electron is removed from the nucleus is called the reference, or zero-energy, state of the hydrogen atom. 

The problem becomes very complicated v hen material bodies exist in the surrounding space. In this case, an adequate solution requires to consider simultaneously at least four systems—the quantum one (the excited nucleus) the electrons of the atom, v/hich contains the excited nucleus the ensemble of electromagnetic modes in the main (vacuum, zero-energy) state interacting v/ith the nucleus and the ensemble of objects surrounding the considered nucleus (the system of N resonant or nonresonant atoms or screen) v/ith v/hich these modes also interact... 

When maintenance and servicing are required on equipment and machines, the energy sources must be isolated and lockout/tagout procedures implemented. The terms zero mechanical state or zero energy state have often been used to describe machines with all energy sources neutralized. These terms have been incorporated in many standards. 

Equipment must be at zero energy state before servicing or maintenance work can begin. To get to this zero energy state, authorized employees ... 

Verifieation is provided by a systen whieh aetively confirms zero-energy state to the drives before the verifieation light eomes on... 

When an individual initiates the loekout sequenee by opening the systen switeh and placing a lock on it, the verification light will come on if the machine is at a zero-energy state... 

Stored electrical energy must be discharged to obtain zero energy state. 

Whenever it is not possible to positively verify that the cavity between double blocks is at zero energy state. 

Use lockout/tagout procedures to achieve a zero-energy state on the equipment. Devices such as locks, tags, chains, or other hardware are to be used for personal safeguarding. 

This is not an unusual story nor is it a rare happenstance. Each year some 120 workers are killed as a result of not ensuring a zero-energy state on the process they are working with. In addition, some 60,000 injuries take place—many of them involving permanent disability. OSHA states that approximately 39 million workers will be protected by this new rule. The electrician discussed above was only protected by the intent of the standard he chose to follow his old habits and not take that extra moment to lockout. 

The power to those particular lights in that aisle is most likely from a master circuit breaker box. To arrive at a zero energy state, the correct breaker box switch must be moved to the ofT position. At this time, a means of preventing someone from moving the switch to the on position is necessary. 

Never attempt to service or repair a conveyor without following procedures for locking and tagging. Bring the unit to a zero-energy state. 

Never remove covers and guards from welding equipment without first bringing the machine to a zero-energy state. 

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