The parties are free to agree on the procedure for appointing the arbitrator or arbitrators, including the procedure for appointing any chairman or umpire.
If or to the extent that there is no such agreement, the following provisions apply.
If the tribunal is to consist of a sole arbitrator, the parties shall jointly appoint the arbitrator not later than 28 days after service of a request in writing by either party to do so.
If the tribunal is to consist of two arbitrators, each party shall appoint one arbitrator not later than 14 days after service of a request in writing by either party to do so.
If the tribunal is to consist of three arbitrators—
If the tribunal is to consist of two arbitrators and an umpire—
In any other case (in particular, if there are more than two parties) section 18 applies as in the case of a failure of the agreed appointment procedure.