In accordance to the spirit of this post, I've dug out one of my old posts and pasted it here. All info can be found in Singapore Statues in AGC's website.
Pursuant to Para 2 of Tobacco (Control of Advertisements and Sale) Act,
"tobacco product means any cigarette, cigar or any other form of tobacco, or any tobacco derivative or substitute, including any mixture containing tobacco, or any tobacco derivative or substitute, but excludes any medicinal product registered under the Medicines Act (Cap.176)
tobacco substitute means any article, object or thing that contains nicotine, but excludes tobacco, tobacco derivatives and any medicinal product registered under the Medicines Act."
use, in relation to any tobacco product, means smoking, chewing, inhaling, ingesting or otherwise introducing the tobacco product or any of its constituents or emissions into the human body (whether by oral means or otherwise);
PV/e-cigs/electronic nicotine delivery devices are, therefore, classified as a Tobacco product/substitute.
Pursuant to Smoking (Prohibition in Certain Places) Act,
smoking, with its grammatical variations, means inhaling and expelling the smoke of tobacco or any other substance and includes the holding of any cigar, cigarette, pipe or any other form of tobacco product which is alight or emitting smoke;
So no you may not vape in places that analogue smoking is prohibited.
If you're wondering whether is it or is it not illegal, as long as HSA says it is illegal, it is illegal. Because the Tobacco (Control of Advertisements and Sale) Act is a statute and it is up to the Chief Executive of HSA to determine it's interpretation of the
regulations stated.