Thermostatic Expansion Valve

Guys,

I'm suppose to order thermostatic expansion valve (txv) and follow the method of calculation as suggested by the supplier to select the exact model no. of txv. Now all their products do not have txv suitable for R407c bec. R407c is what we used as a cooling medium. Our condensing units were manufactured based on R22, and we just replaced R22 with R407c.

I've searched in the internet of that supplier's products and found out that there is a txv suitable for R407c but in stainless steel . I don't want to buy such an expensive txv and our local supplier doesn't have that stainless steel txv.

Now my option is to go with R22 txv since our condensing units were manufactured based on R22. Question, is it safe to use R22 txv when we use R407c as a cooling medium? I have no idea what will be the effect so if any ideas you have there to share please help me. As of the moment I'm still searching for the right answer thru net.