PPH cov kav dej yog cov yam ntxwv los ntawm lawv cov kev tiv thaiv corrosion, kub, thiab siab, ua rau lawv haum rau kev siv tshuaj lom neeg thiab ib puag ncig. Lawv kuj yog lub teeb yuag, yooj yim rau nruab, thiab tus nqi- siv tau, thiab tuaj yeem tiv taus cov tshuaj acidic thiab alkaline. 👍
