Specifications controlled atmosphere controller.docx

Statement of Work – Computerized Control for Controlled Atmosphere System

UDSA-ARS Tree Fruit Research Laboratory 3005 Experiment Station Drive Hood River, OR 97031

Introduction

A controlled atmosphere (CA) system in postharvest fruit storage enables modification of the relative composition of gases surrounding fruit in storage, most critically oxygen (O2), nitrogen (N2), and carbon dioxide (CO2). The purpose of CA, typically in combination with low temperature, is to decrease respiration rate and slow other physiological processes in fruit to allow for increased storage duration. Modification of gases beyond normal atmospheric conditions, while sometimes allowing for increased storage longevity, can provoke low O2 or high CO2 stress conditions in fruit, leading to abiotic disorders. For this reason, postharvest storage research is needed to determine optimal CA conditions as well as the physiological basis of disorders.

We require a computerized control system along with installation to upgrade our existing CA fruit storage research system at the USDA-TFRL in Hood River, OR, as the present CA system is manually controlled and outdated, relative to what is used in industry fruit storage warehouses, which have computerized control and different hardware / manifolds / valves for gas distribution. It is crucial for our research mission that our CA system be comparable to that used in industry settings in order that we can better serve our stakeholders research needs.

Specifications

The system needs to include a control computer, control panel, and software to replace the present manually controlled CA system, including outlet and return/injection valves, O2/CO2 analyzer, and rotometers. The system must be sized for 32 research chambers measuring approximately 28”x 20”x 16”, with 16 of these chambers in each of two cold rooms, and one room measuring 12’3” x 12’ x 8’2”. The sytems may use existing tubing and components where appropriate. Additionally, the control panel and computer software shall have the capacity to monitor and control temperature in 16 chambers and provide digital output to turn on a heating/cooling source in these chambers. Manifolds for gas delivery and autosampling must be supplied. The control panel shall provide refrigeration control, including evaporator fans, a liquid solenoid, and a defrost heat tape circuit where appropriate. Low voltage cable is to be supplied by contractor.

System safety features must include activation of an alarm when a door to a low-oxygen room is opened.

The CA system must also include an automatic alert to selected users via phone message or call when levels of gases or temperatures exceed pre-defined tolerences, as well as allow remote internet-based monitoring of CA room and chamber conditions.

This mission critical equipment requires heavy customization and continuous operation up to 11 months of the year. Therefore the Contractor of this highly customized system must be able to provide appropriate, competent maintenance and repair service, including in-person when required, during the warranty period of this system. We require the availability of emergency service and repairs by the Contractor within 2 hours of detecting any breakdown to maintain experimental integrity. Replacement parts must be stocked by the Contractor and available to avoid detrimental repair delays. The Contractor shall have experience in servicing controlled atmosphere controllers for pome fruit (apples and pears) within the past five years.

Full installation is required. Proposal must include all components and related installation up to but not including electrical and everything downstream of the N2 collection tank (nitrogen generator system) and N2 lines. Installation must include testing with existing nitrogen distribution controls used for controlled atmosphere storage chambers. Equipment specifications and installation must fit existing layout and space restrictions.

Contractors are required to determine whether their equipment can be customized for the provided space. Preproposal site visit is strongly encouraged to ensure compliance with all requirements: please contact the technical and site contact to arrange a site visit.

Contractors must consider available power and ensure that their equipment will work therewith.