1. All persons who are firefighters shall be members as a condition of their employment and shall receive no pension or retirement allowance from any other pension or retirement system supported wholly or in part by the city or the state of Missouri because of years of service for which they are entitled to benefits under this system nor shall they be required to make contributions under any other pension or retirement system of the city or the state of Missouri, anything to the contrary notwithstanding.

2. If any member, in any period of five consecutive years after last becoming a member, is absent from service for more than four years unless the member has twenty years or more of creditable service, or if any member withdraws the member’s accumulated contributions, or if any member becomes a beneficiary, the person shall thereupon cease to be a member; except in the case of a member who has served in the Armed Forces of the United States or retired pursuant to section 87.170 and is subsequently reinstated as a firefighter or as a member in beneficiary status as a surviving spouse.

3. Any member who is reinstated after retiring pursuant to conditions in section 87.170 shall not be eligible to participate in the benefit provided pursuant to section 87.182.