I live in a pier and beam house in south central Texas and getting my floor insulated with spray foam. Any opinions on closed cell versus open cell for this application?

Having used Foam It Green closed cell insulation in my house had having seen open cell used in my another house, my immediate response was going to be closed cell but I'm biased seeing the differences between the 2 applications. I'm a closed cell individual all the way but I'll let the following link provide the reasoning why closed cell is the best way to go for your application needs.

INSULATING A RAISED FLOOR

Hope this helps convince you to go with closed cell for you application.

Thanks for the link very informative, sounds like closed cell is the way to go

Good building science is to use open cell foam since it's not waterproof like closed cell. If your subfloor is wood, water from a plumbing leak will migrate thru the foam, helping to prevent rot. Prevent runoff from ponding under house.

Closed cell every day for floor application. It keeps gasses from permeating through floor from ground. Open cell doesn't do that.