Final answer:
A permanent arbitrator is tasked with resolving all disputes under a labor agreement throughout its life, ensuring timely and impartial dispute resolution.
Step-by-step explanation:
The type of arbitrator who serves as an umpire to resolve all disputes during the life of a labor agreement is known as a permanent arbitrator. This individual is in charge of handling any disputes that arise under the labor contract for its duration, ensuring that the arbitration process is accessible and impartial. A permanent arbitrator provides a timely manner for dispute resolution which is essential in maintaining the effective operation of the agreement.