Product Substitutions and Non-Proprietary Plans

Found in the Quality Assurance section of our specifications we include the following:

"Random product substitutions will not be accepted.  The functionality of the irrigation design and system is based on characteristics of the products listed in these specifications and accompanied plan.  Contractors wishing to substitute any product must submit, in writing, reasons for proposed substitution, product specifications, revised plan, and performance data to the Owner’s Representative and Irrigation Consultant.  If written approval is granted, products may be substituted.  Any products found during the final walk through, not previously approved, will be removed and replaced with an acceptable product at the contractor’s expense."

Similar products can have varying hydraulic characteristics from different manufacturers.  Different flow rates, pressure requirements, and operating ranges.  To minimize sizes due to pressure and flow requirements, a designer has to choose one product to make accurate hydraulic calculations.  Changing products on a plan can require changes in other products, pipe sizing, scheduling, or water requirements.

A non-proprietary plan is almost an open ended plan allowing the contractor to select the products. The products selected must meet the minimum specifications, but can still have varying hydraulic characteristics.  When designing a system, that a specific product is not called out, we need to design for the worse case.  This can lead to higher pressure requirements, larger pipe sizes, larger valve sizes, etc.

The biggest selling point for non-proprietary plans is to avoid a manufacturer having the ability to charge more for their products.  However, contractors typically buy irrigation products from an irrigation distributor.  The manufacturer has no control of pricing per project, the distributor does.  Most distributors carry multiple products from multiple manufacturers.  A contractor has the choice to purchase the materials for each job from two or more local suppliers.  This results in distributors trying to undercut the other for the sale.  Usually on the same product.

When bidding from a plan, the biggest irrigation cost variable is labor.  Most products, of similar quality, are close in price.  Usually the savings is minimal when opting for one manufacturer over another.