Yes, per the manufacturer the Chapin Seal and Gasket Kit (#6-1925) will work for the Chapin 31430 Lawn & Garden Tri Poxy Sprayer.
The Chapin Seal and Gasket Kit (#6-1925) does not contain the parts that would fit the Chapin Chapin 61900 Tree/Turf Professional and Commercial. For that model sprayer, you would need the Chapin Replacement Filter Basket with Cap.
Yes, the material of the parts in the Chapin Seal and Gasket Kit 6-1925 are made of Viton.
