We consumers are also to blame

Had two hardware store bought valves with plastic inner part - and for 13.99 p.Stk. gelöhnt. Before I einbaute I've looked at the bill and it was in the name such as "standing".
Since I wanted to build a but horizontally and did not want to play the guinea pig, I've looked and discovered that there are these valves in a decent version with metal inner part of the net. Could not imagine me anyway quite how cheaply molded plastic inner part is intended to seal.

First, very insecure because of a review here that claims the valve spring would be too strong for a garden pump, but I did it but risked and ordered two.

They are used in a small house waterworks TIP HWW 1000/25 Plus TLS. No sign of allegedly excessive spring. Everything works.
Why two valves? One in front of the pump in the suction line, possibly to prevent the lowering of the water column, and I have a directly mounted at the output in order to avoid vibrations. This second valve is often forgotten. Have had, at a rapid turning of the water, about a ball valve, there can be considerable pressure variations in the line that would be transferred without valve on the pump inside tell me.

I realize more and more that good quality gradually disappears from the ranges and is displaced by tlw. Really bad. I attribute this to the fact that more and more home improvement shopping itself. Our unity has no detailed knowledge why a plumber for example uses a specific expensive spare parts, and experts are not to be found in hardware stores as a seller. So the price is (and increasingly also the design!) The decisive criterion course - and no longer the quality and functionality.
That's why we consumers are sometimes to blame when only scrap is offered or who creates it just beyond the warranty period.

Therefore in at this point by me the indication that these valves are high-quality workmanship, have a longer body and therefore a lower flow resistance than the DIY valves and one with a part that needs to last for decades, not because of three Euros a plastic scrap must depend the line when there are much better quality at a very fair price.