NJK Precision Product NJK-02 Sensor Installation Guide

Transcription

1 Precision -02 Sensor 2017 Product Line Precision Product Table of Contents Precision Company Overview - Page 2-02 Installation Guidelines - Page 3-02 Recommended Installations - Page 5-02 Non-Recommended Installations - Page 7-02 Installation Solutions (Outside Air) - Page 9-02 Installation Solutions (Mixed Air)- Page Installation Solutions (Supply Air) - Page Wiring - Page 21 Page 1

2 -02 Sensor Purchasing Guide Precision Company Overview The Precision Product Overview: The -02 Air Flow Measuring Station is proudly Made in the USA in our Factory located in Eaton Rapids, Michigan. The -02 Air Flow Measuring Station consists of the perimeter sampling aluminum extrusion Flow Frame, a Sensing Module which contains the sensing probe and signal transmitter and is mounted to the Flow Frame and is the one single sensing probe associated with each -02 Air Flow Measuring Station, and a Display Module with User Interface for set up and calibration of each flow station. The Precision Team: Kevin Hein, President Von Weise Companies (kevin.hein@vonweise.com) Nick Wolgamott, Vice President of Engineering PMAS-MAF and Precision Michael Hurd, Factory Representative Precision (michael.hurd@vonweise.com) Robert Pierce, Plant Manager and Design Von Weise Companies Beth Allen, Sales Manager Von Weise Companies (beth.allen@vonweise.com) Page 2

3 -02 - Location and Mounting: Installation Guidelines. All -02 Air Flow Measuring Station installations should be verified by an Sales Representative or Factory Representative as to system effect on the air flow sensor and air flow sensor effect on the air system. System Effects must always be considered when installing an Air Flow Measuring Station to assure that the air flow measured through the Sensor is a true representation of the desired air flow and is not being effected by other air sources such as return air flows or by system dynamics that adversely effect the air flow through the Sensor. System Effects must also be considered to assure that the installation of the Sensor does not create any negative impact on the dynamics of the air system such as stratification, excessive flow restrictions, or low temperature detector (freeze stat) operations. It will be the responsibility of the Sales Representative or direct Ordering Customer to assure that the air flow measured through the Sensor is a true representation of the desired air flow and is not being effected by other air sources such as return air flows or by system dynamics that adversely effect the air flow through the Sensor. It will also be the responsibility of the Sales Representative or direct Ordering Customer to assure that the installation of the Sensor does not create any negative impact on the dynamics of the air system such as stratification, excessive flow restrictions, or low temperature detector (freeze stat) operations. Air Flow Sensor Accuracy is often enhanced by straight, even runs of ductwork that help smooth out air flows and signal noise. The Sensor will perform accurately in these ideal settings. We anticipate that our product may be installed in less than ideal placements such as limited straight duct lengths or ductless (plenums or rain hood) installations. There are some installation situations that should be avoided. Although some customers have found ways to make the Sensor operate effectively in applications that Precision suggests to avoid, Precision will not warrant accuracy or repeatability when the Sensor is installed outside of recommended installation practices. Page 3

4 -02 - Location and Mounting: Installation Guidelines. Do Not install Sensors downstream of damper banks: Place all sensors ahead of damper banks. This will keep the sensor out of mixing chambers and will eliminate poor sensor readings due to damper restrictions and possible return air entrainment. Whenever the Sensor is mounted inside of a mixing air chamber there may be air flow issues caused by internal system effects and air flow dynamics. Do Not install Sensors in an outside air louver section where the Sensor is hanging freely in the OA chamber as this can allow air to swirl on the outlet side of the sensor and may cause a false reading through the Sensor. Do Not install Sensors for branch duct flow measurement directly on a main ducted plenum as the air that will flow in the plenum will inherently create a negative swirling effect at the branch transition and will cause a false reading through the Sensor. If the Sensor is to be mounted in a branch duct off from a main supply plenum have a transitional duct boot installed ahead of the Sensor or move the Sensor further downstream in the branch ductwork to avoid the turbulent flow at the plenum to branch transition. Do Not install Sensors on the face of a Coil or Filter Bank as the coil or filters will become loaded with dirt and debris and will cause a false reading through the Sensor. Do Not install Sensor Modules external to the Flow Frame on the bottom of the Flow Frame as this can allow water to build up inside of the Sensor Module and effect sensor accuracy. This is most often an issue with outside air applications. Do Not install Sensors directly downstream of turning vanes as they can divert air from the perimeter of the ductwork and create an unreliable flow signal through the Sensor. Do Not install Sensors in a supply plenum with a large (or multiple) Centrifugal Fans feeding the air into a supply plenum. That air is distributed unevenly throughout the supply plenum and can also have strong cross flows of air across the face any of the supply duct take offs. Do Not install Sensors in a supply plenum with a large Centrifugal Fan feeding air into the supply plenum tapered bellmouth as the air will turbulent at best. The tapered section of ductwork can allow supplied air to be forced through the center of the duct and bypassing some of the sampled air from the -02 Perimeter Sampling Flow Frame. Page 4

5 -02 - Location and Mounting: Recommended Installations. In the applications above the -02 Air Flow Sensor can be installed with little or no ductwork leading into or out of the -02 Air Flow Sensor. In a supply plenum with Plug or Plenum Centrifugal Fans the air is distributed evenly throughout the entire supply plenum. In this application the -02 Air Flow Sensor can be installed with little or no ductwork leading into the sensor. Page 5

6 -02 - Location and Mounting: Recommended Installations. In the application above the -02 Air Flow Sensor can be installed with little or no ductwork leading into or out of the -02 Air Flow Sensor. In the application below the -02 Air Flow Sensor can be installed in the floor grating or ceiling take off directly with little or no ductwork leading into or out of the -02 Air Flow Sensor. Page 6

7 -02 - Location and Mounting: Non-Recommended Installations! Avoid mounting sensors into any widened duct or any other application where measured air could be forced through the center of the sensor and not accurately sampled. Avoid mounting sensors on the face of any filter banks or coil banks. These items can become filled with debris and force more air through the outside of the unit and through the sensor causing a false raised flow reading when the actual flow has been decreased. Avoid mounting the sensor on the downstream side of a damper set whenever possible. If you do have to install an sensor on the downstream side of the dampers ensure that it is only done with opposed blade dampers to avoid excessive concentrations of air flow in one area of the sensor. No matter what the conditions, once you introduce the sensor into, or near the mixing chamber, you will assume all dynamics and responsibilities of that mixing chamber (air mixing, entrainment, false readings, freeze stat issues). Page 7

8 -02 - Location and Mounting: Non-Recommended Installations! Do Not install Sensors directly downstream of turning vanes as they can divert air from the perimeter of the ductwork and create an unreliable flow signal through the Sensor. Do Not install Sensors for branch duct flow measurement directly on a main supply plenum as the air that will flow in the plenum will inherently create a negative swirling effect at the branch transition and will cause a false reading through the Sensor. If the Sensor is to be mounted in a branch duct off from a main supply plenum have a transitional duct boot installed ahead of the Sensor or move the Sensor further downstream in the branch ductwork to avoid the turbulent flow at the plenum to branch transition. Page 8 Do Not install Sensors in an outside air louver section where the Sensor is hanging freely in the OA chamber as this can allow air to swirl on the outlet side of the sensor and may cause a false reading through the Sensor. (See Page #10)

9 -02 - Location and Mounting: Installation Solutions Installation #2 (Non-Recommended) Installation #1 (Recommended) -02 sensor without angle flange. Add a 1 inch, 90 degree angle flange around face of -02 air flow sensor. In an open air installation (such as an outside air or open plenum) feeding inlet application the Sensor will need to have a 1 inch sheet metal angle bracket installed on the leading edge of the sensor Flow Frame. This will serve as a velocity stack and will help prevent entering air from circling around the sensor inlet and potentially being missed in the sampling process. The sheet metal angle flange can be flush with the face of the Flow Frame or can extend slightly outward. The operation of the Sensor without the angle bracket will still be functional but the signal will be very unstable and difficult to settle down. Strong cross flows can essentially blow by the inlet ports of the Flow Frame. Page 9

10 -02 - Location and Mounting: Installation Solutions Installation #2 (Non-Recommended) Installation #1 (Recommended) Outside Air Chamber Exterior Wall Outside Air Chamber Exterior Wall Block Wall Sensor Air Flow Block Wall Sensor Air Flow Eddy Currents Air Flow Exterior Wall Air Flow Exterior Wall Outside Air Dampers Outside Air Dampers In the mounting installation above the Sensor Flow Frame is to be mounted in an exterior wall inlet directly after the inlet rain louvers. Installation #1 allows for air to enter and exit the sensor with smooth flow and dependable flow readings. Installation #2 has the exiting side of the Sensor Flow Frame suspended into the outdoor air chamber and can have the ability to allow reverse eddy currents on the leaving edge of the Sensor. This may give an altered air flow reading and can be avoided by placing the Sensor more centered on the exterior wall opening. In the mounting installation to the right the Sensor Flow Frame is to be mounted in an exterior wall inlet directly above the outside air dampers. An Sensor mounted just below exterior wall opening can allow outside air to pass the leading edge of the sensor frame. Mounting the sensor frame closer to the exterior wall edge will force most of the air through one edge of the sensor frame. Moving the Sensor Flow Frame closer to the dampers will allow better flow through the entire sensor. Air Flow Sensor Outside Air Dampers Exterior Wall Air Flow Page 10

11 -02 - Location and Mounting: Installation Solutions Installation #2 (Non-Recommended) In this mounting installation the Sensor Flow Frame is mounted in an area where the air flow will be very strong on one area of the opening with a high air velocity and the air flow will be very minimal or non-existent on the opposite side of the Flow Frame. If the Sensor Module is mounted on the low velocity side of the Flow Frame where air velocities can be less than 25% (see #1 Below) of the average air velocity across the flow frame there is a risk that sampled air can be drawn from the Sensor Module and cause the Sensor to read a lower than actual air flow. This can become an issue whether the air flow is being supplied or returned. Sensor Module / Probe Extremely Low Air Velocity Extremely High Air Velocity Installation #1 (Recommended) Sensor Module / Probe Extremely Low Air Velocity To resolve this locate the Sensor Module on the Higher air velocity side of the Sensor Flow Frame to allow the sensing probe to accurately measure the sampled air from the flow frame. Extremely High Air Velocity #1 - A 25% air velocity minimum or greater will allow for an open consideration when locating the Sensor Module. System Effects must be considered when locating the Sensor Module. Any installation where placement of the module is in an area with an air flow velocity below 25% of the average velocity can not be guaranteed for accuracy and signal dependability. Page 11

12 -02 - Location and Mounting: Installation Solutions Installation (Problem) Installation (Solution) Outside Air Inlet Hoods are often located in close proximity to the relief or exhaust dampers on many rooftop and packaged units. Caution must be utilized when installing sensors in these areas to ensure that the addition of an Sensor mounted on the end of an outside air intake does not allow the sensor to protrude into the exhaust air stream causing an unwanted system entrainment effect. Mount the Sensor inside of a rain hood or outside air inlet opening to assure that the factory system dynamics of the rooftop or packaged unit are not altered Page 12

13 -02 - Location and Mounting: Installation Solutions Problem: In a Mixed Air Plenum the return air can be forced back into the outside air duct if the total air system is out of balance or out of sequence. This condition will create an errant reading with the outside air sensor. In this situation the -02 Air Flow Sensor will read reverse air flow as regular flow. Solution: The air handling system must be in complete balance and under optimal control conditions to assure that return air is not being forced backwards through the outside air ductwork and flow sensor. Problem: In a Mixed Air Plenum the return air can be forced back into the outside air duct when the HVAC system is in a full recirculating mode if the outside air dampers do not completely close off. This condition will create a flow reading through the outside air sensor when the outside air flow is believed to zero. In this situation the -02 Air Flow Sensor will read reverse air flow as regular flow. Solution: The air handler outside air dampers must be adjusted so that they close off completely. Page 13

14 -02 - Location and Mounting: Installation Solutions Installation (Problem) Installation (Solution) Return Air Outside Air Mixed Air Sensor installed on outside air Return air collides with Flow Sheet metal added to direct return air Problem: In a Retrofit application the return air can be forced back into the outside air duct due to a lack of available space in an existing mechanical room. This condition will create an errant reading with the outside air sensor. In this situation the -02 Air Flow Sensor will read reverse air flow as regular flow. Solution: Sheet metal diverting plates may need to be engineered to assure that return air is not being forced backwards through the outside air ductwork and flow sensor. Page 14

15 -02 - Location and Mounting: Installation Solutions Installation #2 (Problem) Installation #1 (Solution) Minimum of 4 Duct Diameters In a supply plenum with a large Centrifugal Fan feeding air into the supply plenum tapered bellmouth the air will be turbulent. The tapered section of ductwork can allow supplied air to be forced through the center of the duct bypassing some of the sampled air from the -02 Perimeter Sampling Flow Frame. In this application the -02 Air Flow Sensor can NOT be installed without some lengths (Minimum 4 duct diameters) of straight ductwork leading into the sensor and the -02 will need to be installed further downstream in that straight duct length. This installation will have a very unstable flow reading through the -02 air flow sensor as the flow off from each blade of the centrifugal fan will have an impact on the sensor reading. Page 15

16 -02 - Location and Mounting: Installation Solutions Minimum of 4 Duct Diameters Minimum of 4 Duct Diameters Minimum of 4 Duct Diameters Locate Sensor as far downstream as possible (Minimum of 4 duct diameters) to avoid air turbulence and entrainment. Solution: Locate Sensor as far downstream as possible (Minimum of 4 duct diameters) to avoid air turbulence and entrainment. Solution: Problem: In a supply plenum with a large (or multiple) Centrifugal Fans feeding the air into the supply plenum that air is distributed unevenly throughout the supply plenum and can also have strong cross flows of air across the face any of the supply duct take offs. In this application the -02 Air Flow Sensor can NOT be installed without ductwork leading into the sensor and the -02 will need to be installed further downstream in each of the individual duct runs. Page 16

17 -02 - Location and Mounting: Installation Solutions Minimum 4 Duct Diameters Minimum 4 Duct Diameters Installation (Problem) Locate Sensor as far downstream as possible (Minimum of 4 duct diameters) to avoid air turbulence and entrainment. Installation (Solution) Locate Sensor as far downstream as possible (Minimum of 4 duct diameters) to avoid air turbulence and entrainment. Installation (Solution) In a supply plenum with a Supply Fan feeding air at a right angle into the supply plenum the air will be turbulent as it changes flow direction. In this application the -02 Air Flow Sensor can NOT be installed without some lengths of straight ductwork leading into the sensor and the -02 will need to be installed further downstream in the straight duct lengths. Page 17

18 -02 - Location and Mounting: Installation Solutions Minimum 4 Duct Diameters In -Line Supply or Return Fan Minimum 4 Duct Diameters Installation (Solution) Locate Sensor as far downstream from fan as possible (Minimum of 4 duct diameters) to avoid air turbulence. Installation (Solution) Locate Sensor as far upstream from fan as possible (Minimum of 4 duct diameters) to avoid air turbulence. Do not place Sensors in close proximity to any fan system. In-Line Fans of any type will have a pulsating air flow signal based on the air delivered by each blade. In the above application the -02 Air Flow Sensor can NOT be installed without some lengths of straight ductwork leading into the sensor and the -02 will need to be installed further downstream or upstream in the straight duct lengths. This installation will have a very unstable flow reading through the -02 air flow sensor as the flow off from each blade of the fan will have an impact on the sensor reading. Page 18

19 -02 - Location and Mounting: Installation Solutions Problem: Sensors mounted directly adjacent to plenum airflow and are affected by air directional changes that are turbulent causing a swirling effect at the inlet of the sensor frame which will offer a poor air flow reading. AFMS AFMS AFMS Air Flow Solution: install sensors downstream on the inlet of the VAV Box. This will allow the Sensors to accurately read flow at the VAV Box and will be out of the turbulent air at the branch duct connections to the main plenum. VAV Box VAV Box AFMS VAV Box AFMS AFMS Air Flow Page 19

20 -02 - Location and Mounting: Installation Solutions Problem: Outside air minimum and maximum dampers located in a shared plenum can allow minimum air flow to pass through maximum air flow sensor when maximum dampers are closed causing a false reading through the maximum air sensor Solution: Install sheet metal extension sleeves on both the minimum and maximum outside damper inlets to direct the air into the proper sensor and to eliminate false readings through sensors on unopened dampers. Page 20

21 -02 Wiring and Electrical The Display/Operator Interface will receive 24 VDC power from the control electrician. Sensor Probe and Transmitter will be powered from the Display/Operator Interface. Building Automation wiring and 24 VDC wiring will be done via a termination block in the Display/Operator Interface only. Optional 24 VAC Wiring (see below). Sensor Power Requirements: All wiring to Sensor shall be a 4-wire. 24 VDC power/common and 0 to 10 VDC signal/common. Direct Current Wiring (24 VDC): Sensors powered from the same 24 VDC power source as the Building Automation System control field panel should operate without any issues with either the electrical or the BAS signal. Optional Wiring: (Alternating Current Wiring-24 VAC): An Isolated Transformer(s) will be required to power the 24 VAC power for the Sensors if either of the following situations are true. -02 Display Display / Operator Interface 4-3/4 If the Sensors will be powered by a 24 VAC power system that has any part of the power transformer or system externally earth grounded to a building electric casing or panel buss bar or field panel. Or, if the Sensors will be powered from a different transformer source than the building automation system /4 Termination block located behind Display/O.I. Cover External Wiring Sensor RJ-45 Page 21