>suction I don't know whether to laugh or cry. I operated such a system on a US Navy ship. I have mixed feelings about it. There are rubber flappers that ne

>suction I don't know whether to laugh or cry. I operated such a system on a US Navy ship. I have mixed feelings about it. There are rubber flappers that needs to be replaced often to maintain the vacuum. It's just a simple piece of rubber in an easy-to-produce shape. The price per flapper in the inventory system was $200-something.