1.11.005 Thermostatic Valve (on Screw Compressor Oil piping)

This Policy is completed and waiting Field Service, Engineering, and EHSS approval.

Purpose

The purpose of this procedure is to establish the minimum requirements for understanding the basics of how the compressor oil thermostatic valve controls injection oil temperature on Screw Compressors on Flogistix FX model units.  The procedure applies to all Flogistix FX model screw compressor units.  

Procedure

This procedure applies to all Flogistix FX model screw compressor units that are currently in service in the Field, Test Loop, at a Repair Shop, or in Storage Yards.  

The Thermostatic Valve on the screw compressor oil piping system is what is used to control the injection oil temperature going to the rotary screw.. 

The compressor oil piping system is described in detail on the Field Service Wiki procedure 1.11.04 FX Screw Compressor Oil Piping with the following link:  1.11.04 FX Screw Compressor Oil Piping

The example below shows the location and the orientation of the Thermostatic valve in the screw compressor oil piping system.

Thermostatic Valve

There are three ports in the Thermostatic Valve The ports are either stamped or cast with the letters A, B, & C.

Port A

When set up as Blending Port A – Is the temperature of the controlled oil going to the screw compressor.

Once full temperature is reached, the flow out of port A should be at the temperature that the valve’s installed thermostat is designed for, +/- 10 degrees F. 

The default thermostatic valve is 230 degrees on newer FX series units.  Higher temps may be required for certain applications.

Port B

Port B – Is the hot Oil coming from the Discharge Vessel. (as shown in the example below)

If the oil is not hotter than the thermostatic element it will bypass the cooler and go directly into the B Port of the thermostatic valve. 

If the oil is hotter than the thermostatic element it will be forced to go into the cooler. 

Port C

Port C – Hot oil that has gone through the oil cooler will exit the cooler and then go into Port C of the thermostatic valve. 

A good way to remember the ports on a thermostatic valve that is either set up for Blending or Diverting is:

Port A – Is the temperature that is controlled.

Port B- Is the Bypass

Port C- is going to or from the Cooler

Two ways a thermostatic valve can be piped.

Blending

Blending is the way new or current way Flogistix units are set up.

When the thermostatic valve is set up for Blending the thermostat is keeping the injection oil at the temperature of the thermostatic element.  

A good way to remember the ports on a thermostatic valve set up for Blending is:

Port A – Is the temperature that is controlled going to the compressor injection.

Port B- Is the Bypass

Port C- is oil coming from the Cooler

Diverting

Diverting is the way the older Flogistix and FCP units were set up.

When the thermostatic valve is set up for Diverting the thermostat is keeping the Discharge vessel at the temperature of the thermostatic element.  

A good way to remember the ports on a thermostatic valve set up Diverting is:

Port A – Is the temperature that is controlled coming out of the discharge vessel.

Port B- Is the Bypass

Port C- is oil going to the Cooler

There are different temperature range thermostatic elements that can be installed to achieve the required oil injection temperature

If the oil injection temperature stays below the Low Injection Temperature set point in the panel after the set time period it will shut the compressor down. 

This is a hard fault shutdown and not an auto restart option.

Running below the set point of the Oil Injection temperature will result in low discharge temperatures that could be below the Dew Point of the compressed gas. 

This could lead to Oil dilution or condensate build up in the compressor oil.  

This is discussed on the Field Service Wiki 1.5.01 Minimum Viscosity Limits for Poly Glycol Synthetic Screw Compressor Oil 1.5.01 Minimum Viscosity Limits for Poly Glycol Synthetic Screw Compressor Oil

Responsibilities

Management - Management is responsible for implementing, supporting, and enforcing the requirements of this procedure to their respective locations/area.

EHSS - Responsible to assist in the implementation of this procedure and to review for effectiveness.

Employees, Contractors, Vendors, ETC. - Are responsible to follow the requirements outlined in this procedure and ask for assistance

Scope

This procedure applies to all Flogistix FX model screw compressor units and are applicable to all Flogistix employees, contractors, and temporary employees.

Hazards

Employees should be aware that units could contain flammable and toxic gasses.  Potential for the possible hazards of gas ignition or fire, hot surfaces & fluids, rotating equipment.  Risk of possible concentration of H2S.  Hazardous gases could be in the units pressure vessels, cooler, or associated piping and risk of inhalation of hazardous gas fumes.  

Safety

All Personal Protective Equipment (PPE) for normal Field Mechanical duties apply for this procedure.  

Four Gas Monitor, which is outlined in the Flogistix EHSS Manual, PPE Section 8, Procedure 8.3 

This procedure applies to all units in service in the field, at a service shop, or in any storage yard.

Insure Flogistix personnel have proper safety certification or site orientation if required by the Flogistix Customer.

Insure Flogistix personnel adhere to all Customers safety practices.

Training

All employees shall be initially trained on the following topics:

• Employee Personal Protective Equipment (PPE)

• Lock Out Tag Out (LOTO) procedure according to Flogistix policy

• Emergency and First Aid procedures

• Methods and Observations that may be used to detect the presence or release of a hazardous chemicals or gas in the work place

Tools & Equipment Required

All employees performing this procedure shall be required to have the listed tools to perform job tasks:

• All required PPE according to Flogistix Safety Policy

Approvals

Field Service approved by: 

Date: 

Engineering approved by:

Date:

EHSS approved by:

Date: