Words I have added or changed are marked by [ and ]. The marker  shows where I have deleted words. The | indicates you must make a choice of one or other word. Remember to remove my markup (the [ and ]) before sending.
This [email|letter|other] [is to] request your approval to purchase [a] new 10KVA UPS that will be used as a backup power supply for servers. Most of the time power failure[s] occurred [at night] and no administrator [was] around to  shutdown the server [properly]. The improper shutdown of servers cause[d] corruption of data which result[ed] [in] system failure[s].
The existing UPS, that we bought [in the middle] of 2001, is already worn-out and  its battery power [has] degraded. This UPS is not reliable [for] use [with the] servers because of its short run time and can only be used on small equipment like modem[s], routers and hubs.
When approved, the UPS shall be used to supply power to mission critical servers like Email, Platinum and storage server[s] for [the] editorial group.
The APC SURT 10000 XLI UPS comes with [a] standard battery pack and when [under] full load can only run for maximum of 4 minutes. To extend [the] run time, we need an additional battery pack. The additional of two (2) external batteries is recommended to extend [the APC SURT 10000 XLI UPS's] run time  to at least 45 minutes.