“Safe” is a somewhat relative term. There’s really no way anyone can give you a reliable answer to your question, or, this question without clarifying some things about you. For example, your propensity for injury/strain, any prior knee injuries, and, your ability to recover from each session to name a few. In all actuality, weight training/exercise is not a risk free activity. It’s designed to put stress on your muscles and joints so that growth can be accomplished. And, that’s why some clubs/gyms make their members sign waivers when they join.
You are not guaranteed to be injury/strain free even if your form is perfect. Overuse Syndrome is common for beginner weight trainers. The most you can hope for is to reduce the risk of injury by using correct form, recovering sufficiently from each session, and supporting your efforts with a nutritionally sound diet.