Let’s start with what happens when some solvents are out-of-date. Solvents containing alcohol are hydroscopic, so absorb moisture from the air. What starts as 0.2% moisture could drift up to an unacceptable purity level, as it is exposed to ambient air. If sealed, this will happen extremely slowly. That depends on the packaging and sealing method, which we have full control of.
Once a container is opened, we no longer have control of it, so it is impossible to give a credible number. If you close it after every use, and have a humidity controlled environment, the same shelf life is probably still applicable. If you leave the container open and you are in the tropics, it will probably pass that unacceptable threshold a lot more quickly.
Whether or not 0.5%, 1%, or 10% moisture contamination is acceptable for your operation depends on what you are doing with it. Some aerospace customers absolutely demand their isopropyl alcohol (IPA) is 99.8% pure, so they manage their inventory very carefully. Other customers dilute 99.8% IPA with DI water to make their own 70% IPA for cleaning stencils. There really necessarily a real-world expiration date for that level of criticality.
Yes, HDPE (plastic) drums are designed to accept commonly available 2” threaded spigots / spouts. Spigots are available at distributors, like at https://www.grainger.com/product/GRAINGER-APPROVED-Drum-Tap-6PFN4.
Yes, the cap can be replaced with a commonly available 2” threaded faucets/spouts. To use: 1) Remove existing cap, 2) replace with 2" faucet cap, 3) make sure faucet is in the off position, 4) turn canister on its side so faucet is pointing up. below and check faucet for leaks Faucets are available from dealers such as https://www.grainger.com/product/DYNALON-Faucet-Includes-Closure-3UDG9.
There is a ratcheted ring on the bottom of the cap, which locks the cap into place and prevents it from unscrewing during shipment. To remove, insert a flathead screwdriver between the cap and the ring and pry it loose so the perforations break free. Then remove the ring. It is similar to removing the tamper-proof lock on a plastic jug of milk.
The shelf life of a product can be found on either the technical data sheet (TDS), available on the product page, or by looking on the certificate on conformance (COC). The COC can be downloaded by going to https://www.techspray.com/coc. Once you have the shelf life, you will need to add it to the manufacture date for a use-by date. The manufacture date can be identified by the batch number. The batch code used on most of our products are manufacture dates in the Julian Date format. The format is YYDDD, where YY = year, DDD = day. For example, 19200 translates to the 200th day of 2019, or July 19, 2019. This webpage explains and provides charts to help interpret our batch numbers: https://www.techspray.com/batch-codes.