Tempero Systems Inc. Proposal for a Shower Temperature Control

Transcription

School of Engineering Science
Simon Fraser University, Burnaby, B.C. V5A 1S6
[email protected]
September 20, 2004
Dr. Andrew Rawicz
School of Engineering Science
Simon Fraser University
Burnaby, B.C. V5A 1S6
Re: ENSC 340 Project Proposal for TemperSure
Dear Dr. Rawicz,
Please find attached a copy of the Tempero TemperSure project proposal. With the
TemperSure system installed, a user can set the desired temperature for the shower and
TemperSure will maintain that temperature. In addition, the temperature sensing module
can be detached and used as a portable scalding prevention device. Our purpose is to
eliminate the cases of scalding of children.
Our proposal contains more information on the purpose of our project, some of the
solutions we considered, and the solution we devised. Our plan to build TemperSure
includes a detailed timeline for a completed model by December 2004 and a budget with
sources of funding we will explore.
Tempero is composed of four highly competent fourth year electronics and computer
engineering students with diverse strengths and technical experiences. In the attached
proposal, you can find more information on Mr. Stephen Au-Yeung, Mr. Francis Merin,
Ms. Linda Ni, Mr. Victor Tai, and Mr. Jason Wong, and their role within Tempero
Systems.
If you have any questions or comments please to contact us by e-mail at
[email protected]. Alternatively, you may contact me directly by
telephone at 604-254-7492.
Sincerely,
Jason Wong
CEO
Tempero Systems
Enclosure: Tempero Systems project proposal for TemperSure
Enclosure: Tempero Systems project proposal for TemperSure
Proposal for Shower Temperature Control System
Copyright © 2004 Tempero Systems
Executive Summary
Do you hate it when you are taking a shower and suddenly, because someone in the
house is doing laundry, flushing a toilet, or washing dishes, the water becomes so frigid it
causes you to stop or jump out of the shower? Or consider the opposite case when the
water in your shower becomes too hot and starts to burn your skin.
A study done by Health Canada [2000] shows that out of all pediatric hospital cases,
about a third (32.4%) are because of injuries due to scalding by hot water because of
human error [4], that is, someone had mistakenly either turned on the hot water or turned
off the cold water. Another 12.3% of the cases are of children being scalded when put
into water, either in the bathtub or sink, that was too hot [4]. Tempero Systems proposes
to prevent such injuries which account for half (44.7%) of pediatric hospital cases with
TemperSure.
TemperSure is a temperature control system for the shower, which consists of two valueadded features: a portable scalding prevention shower head add-on, and motorized valves
and solenoid valves for on-demand temperature adjustments and emergency water
stoppage. With the full TemperSure system installed, you simply set a desired
temperature on the digital display and turn on the shower. You can step into the shower
without worrying about the temperature changing, not to mention the comfort of having
the temperature of your shower catered to your need. If the water pressure does happen
to change, TemperSure is equipped with motorized valves that will automatically adjust
to maintain the temperature. In extreme cases where the water temperature cannot be
maintained, the shower will stop running assuring you will never be scaled by water
much too hot for your skin. To continue the shower, you turn on the shower as you did
before starting your shower.
Tempero Systems consists of five engineering students from Simon Fraser University
with backgrounds and strengths in both hardware and software. Group members also
have diverse coop experience bringing diverse assets to Tempero. Most importantly, all
team members are hard working individuals with great communications skills, which
results in excellent team dynamics at Tempero.
We have allotted a four-month development cycle, with a completion date of December
5th, 2004, for TemperSure, which includes completion of a working model, functional
specifications, design specifications, and a post-mortem. The costs associated with
TemperSure are estimated, with careful allowances, at $620 CND. Funding of
TemperSure will come from various funds we are applying to, along with asking for
donations.
ii
Table of Contents
Executive Summary ............................................................................................................ ii
Table of Contents............................................................................................................... iii
List of Figures .................................................................................................................... iv
List of Tables ..................................................................................................................... iv
Glossary ............................................................................................................................. iv
1.
Introduction................................................................................................................ 1
2.
System Overview ....................................................................................................... 2
3.
Possible Design Solutions.......................................................................................... 3
3.1.
Employing a Care Giver ..................................................................................... 3
3.2.
Safety Control Valves ......................................................................................... 3
3.3.
Digitally Controlled Shower System .................................................................. 3
4.
Proposed Design Solution.......................................................................................... 4
5.
Sources of Information .............................................................................................. 5
6.
Finances ..................................................................................................................... 6
6.1.
Budget ................................................................................................................. 6
6.2.
Funding ............................................................................................................... 6
7.
Schedule..................................................................................................................... 7
8.
Team Organization..................................................................................................... 9
9.
Company Profile ........................................................................................................ 9
10.
Conclusion ............................................................................................................... 11
11.
References................................................................................................................ 12
iii
List of Figures
Figure 1: Shower Temperature Control System Overview................................................. 2
Figure 2: Schematic of Shower Temperature Control System ........................................... 4
Figure 3: Gantt Chart of Project Deliverables and Major Milestones ................................ 7
Figure 4: Gantt Chart of Research and Design Tasks......................................................... 7
Figure 5: Gantt Chart of Assembly and Development Tasks ............................................. 8
Figure 6: Gantt Chart of Integration and Testing Tasks ..................................................... 8
List of Tables
Table 1: Advantages/Disadvantages of ASSE 1016 Safety Control Valves ...................... 3
Table 2: Project Budget ...................................................................................................... 6
Glossary
ASSE
American Society of Sanitary Engineering
ESSEF
Engineering Science Student Endowment Fund
TemperSure
Shower Temperature Control System by Tempero Systems
HW
Hardware
Type P
Pressure Balanced Valve specified in ASSE Standard #1016
SW
Software
Type T
Thermostatic Valve specified in ASSE Standard #1016
Type T/P
Combined Thermostatic/Pressure Balanced Valve specified in
ASSE Standard #1016
iv
1. Introduction
A survey conducted by Powers, a manufacturer of temperature controls, in May 2004
indicates that 92% of hotel rooms surveyed have showers that deliver water at scalding
temperatures greater than 115ºF (51ºC) [6].
Many people, especially children, are burned by hot water yearly. A study done by
Health Canada indicates the cause of 32.4% of children injured by hot water is human
error where someone has turned on the hot water or turned off the cold water [4].
For the average home user, shower and bath temperature control is achieved by adjusting
shower/faucet handles while cautiously sensing with one’s hand the water temperature
delivered by a water fixture. For a user in the shower, scalding may occur because of
water flow changes caused by simultaneous usage of water by others in the house.
For the hotel patron, there is an increased danger for scalding because of the greater
chance of simultaneous showers/baths. The conventional “adjust-and-feel” method of
temperature control must be used but again is no guarantee of the comfort and safety of
the water temperature provided by the shower.
Pressure balancing valves on shower/bath fixtures may regulate water temperature,
however, manufacturers of these valves suggest that their temperature stop limits should
be periodically adjusted to maintain temperature control in the midst of water temperature
changes [6]. Water temperatures cannot simply be made lower but must be maintained at
50º C (122º F) for water flowing through pipes to prevent the growth of a pneumoniacausing bacterium known as Legionella [6]. Temperature regulating valves and
combination temperature/pressure regulating valves are possible yet costly alternatives
[3].
The goals of our project are to reduce the need for the “adjust-and-feel” method of
temperature control, and to develop a solution to ensure comfort and most of all, safety,
for shower/bath users. We also aim at providing a solution for automatically adjusting to
water temperature changes for commercial/institutional uses to reduce the need for
manual valve maintenance.
We at Tempero Systems envision designing, developing, and testing an electronic
temperature control system for showers/baths. The following document provides an
overview of our project in terms of design considerations, sources of information,
financial considerations, project schedule, and team dynamics. A profile of members is
also included.
1
2. System Overview
The Tempero Systems TemperSure is an electronically controlled bath system, which
allows users to control the water temperature via a digital control panel. It includes two
electronically controlled valves for adjusting the flow rate for hot and cold water, a
microprocessor for signal processing, and a control panel for usability. Water temperature
is monitored through a temperature-sensing unit located in between the shower pipe and
the showerhead. The system is designed with a three temperature preset memory function
so different household members can enjoy an ideal shower every time.
In addition to the evident user conveniences, the temperature sensing unit, located just
before the showerhead, is also a portable scalding prevention device. When water
temperature reaches 45 ºC (113 ºF), a built-in solenoid valve will shut off the water
supply to prevent the user from being scalded.
Figure 1: Shower Temperature Control System Overview
2
3. Possible Design Solutions
3.1. Employing a Care Giver
A personal care giver could monitor elderly persons or children while showing.
However, hiring a care giver is costly and would require continuous service costs. In
addition, individuals have their own tastes when it comes to a comfortable shower
temperature. Even with the employment of a care giver, changes in cold water flow
within the plumbing system cannot possibly be anticipated. The care giver still needs to
adjust the water temperature manually and unfortunately can only assist a person after a
scalding incident, but not prevent it altogether.
3.2. Safety Control Valves
Safety control valves specified by the American Society of Sanitary Engineers (ASSE) in
Standard #1016 include pressure balancing (Type P), thermostatic, or temperatureregulating (Type T), and combination temperature/pressure-regulating (Type T/P) valves
that are attached to fixtures that can be adjusted by shower users [1]. Each of the safety
valves has advantages and disadvantages as given in Table 1.
Table 1: Advantages/Disadvantages of ASSE 1016 Safety Control Valves
1
Type P [7]
Advantages
• Inexpensive
• Protection from water pressure
changes
Type T [7]1
•
Protection from water temperature
changes
Type T/P
•
Adjustments based on both
temperature and pressure changes
[7]
Disadvantages
• Susceptible to water temperature
changes
• Requires periodic manual
adjustment of temperature limit stop
• Susceptible to water pressure
changes
• More expensive than Type P
• More expensive than Type T [3]
3.3. Digitally Controlled Shower System
The implementation of the shower system that digitally controls water temperature offers
users enhancements in reducing the potential of harm or shock from cold or hot water
temperature changes provided by a shower. By setting the desired temperature and one
click on the switch, users can enjoy a comfortable stream of water. There are different
ways of designing and implementing the shower system in terms of device components
and system schematics.
Ondine, a company of Interbath, Inc., an international manufacturer of shower products,
markets an expensive luxury electronic shower system with the functionality just
described [5].
1
All points in this column are from [7].
3
4. Proposed Design Solution
Figure 2 provides a schematic of the proposed design for our shower temperature control
system.
Cold
Water
Hot
Water
Figure 2: Schematic of Shower Temperature Control System
(M = Motor-driven valve, S = Solenoid valve)
With the system in Figure 2, several design goals must be met when considering the type
of implementation:
•
•
•
Shutoff water flow in the event of water temperature exceeding a threshold
Set desired temperature via a user friendly interface
Maintain a set temperature within a range of ±1 ºC
With these goals in mind, the design of the electronic shower system will consist of two
plunger (gate) type valves controlling the hot/cold water pipes and a solenoid valve after
the mixing point to control water flow. The plunger valves will have the same radius as
the water pipes so that they can be driven easily. Using DC motors for changing valve
positions, the cost of the system is reduced while maintaining the precise movements we
require from the valves. The placement of flow control valves along the hot/cold water
pipes allows for more refinement in the mixture of water. Each pipe is independently
capable of changing its water flow according to commands from the microcontroller. The
solenoid valve after the mixing point allows us to shut off the water flow quickly in the
event that the water temperature rises over a set point.
4
Our proposed design can be separated into two major modules:
• The shower head, LCD display panel and control panel and the motor-controlled
valves
• The temperature sensing unit with solenoid valves
For future commercialized systems, the two modules can be sold separately, giving
customers a choice in system flexibility. Module 2 can be used as a simple, portable
scalding prevention device while the addition of Module 1 in combination of Module 2
provides stable and constant output temperature.
Considering time and budget constraints, the complete system will be only a proof-ofconcept prototype designed to be integrated with an existing shower plumbing system. In
addition, adherence to ASSE Standard 1070-2004 for temperature limiting devices [2] is
beyond the scope of the project but could be considered when developing a final
marketable prototype.
5. Sources of Information
Our group was inspired by an idea proposed by Chao Cheng for reducing the occurrence
of hot water scalding. Cheng is currently the Manager of Technical Support for the
School of Computing Science at Simon Fraser University. His idea is a device that could
be retrofitted onto existing shower heads and be used in hotel suites for warning the
elderly of dangerous scalding temperatures. We will adopt and elaborate his concept to
prevent shower accidents proactively using the design solution proposed in the previous
section. After listening to our project plan, he has shown interest in the development of
the project and has gladly offered his assistance during the course of the project.
Faculty members at Simon Fraser University are also a great source for information and
support. During our research, Dr. Shahram Payandeh, with his expertise on mechanics
and robotics, has suggested types of valves to use, ways to calculate torque required to
turn on valves and methods to attach the motors to the valves. In addition, Dr. Albert
Leung, who specializes in microsensor and actuator fabrication, has offered opinions on
possible thermoprobe materials.
The Internet has been a tremendous resource for our project. We have been able to
contact the technical department of ASCO Valve Inc. through e-mail for information on
the different types of valves available in the industry. ASCO Valve Inc is a well-known
company specializing in fluid control mechanics; their expertise in that area will be
welcomed since most of our team members have little knowledge of fluid control
implementation.
The Honeywell website contains many documents on underground water heating control
logic, which may be useful in developing our temperature control module. These
documents not only provide possible implementation ideas, but also have real life
examples on some of the implementation. Likewise, the Omega Engineering Inc. and the
National Semiconductor websites provide a wealth of information on various temperature
sensor implementations and practical guidelines for applications.
5
6. Finances
6.1. Budget
Table 2 shows the estimated cost for the development of TemperSure. The parts
indicated include all minor associated parts such as resistors, capacitors, and wires. The
costs will be updated as numbers that are more concrete are realized. We will attempt to
reduce costs by asking part distributors for evaluation/sample parts. The estimated costs
in Table 2 below are taken from DigiKey2, unless otherwise noted.
Table 2: Project Budget
Part
Motorized Valves (two units)
·
½ inch valves3
·
DC geared motors
·
IR sensors
·
Mounting equipment
·
H-bridge
User Input
·
LED display
·
Push buttons
Temperature Sensing Unit
·
Pipe2
·
Temperature sensors4
·
Thermometer circuit
Power Supply
Solenoid Stop Valve
Microcontroller
Piping3
10% contingency
Total Cost
Estimated
Cost ($CND)
220
15
120
20
50
15
15
10
5
65
5
50
10
30
135
50
50
55
$620
6.2. Funding
In order to fund the costly research and development of TemperSure, we will be applying
for various grants and asking for donations. In particular, we will be applying to the
Engineering Science Student Endowment Fund (ESSEF) and the Wighton Engineering
Development Fund. Approaching faculty members for donations is another avenue of
funding we plan to explore.
In case funding does not materialize, or we obtain partial funding, each member of
Tempero has agreed to contribute up to $150, which should cover all costs associated
with TemperSure. Team members are purchase parts on their own, however, costs will
be divided evenly among all members.
2
www.digikey.ca
Based on costs from Home Depot
4
Based on costs from www.omega.com
3
6
7. Schedule
The Gantt charts in Figures 3 to 6 present the scheduling of deliverables, milestones, and
project tasks to be completed from September 2004 to December 2004.
Aug Sep Sep Sep Sep Oct Oct Oct Oct Nov Nov Nov Nov Nov Dec Dec Dec Dec
31 7 14 21 28
5 12 19 26 2
9
16 23 30 7 14 21 28
Project Proposal
09/20
First Progress Report
10/04
Functional Specification
10/18
Design Specification
11/01
Second Progress Report
11/15
Post-Mortem Report
12/08
Extra Documentation
12/01
Component Research & Selection
10/20
Preliminary Mechanical/Electrical HW Designs
10/12
Mechanical/Electrical HW Assembly
10/21
Softw are Development
10/23
Integration of SW & HW Modules
11/07
Testing & Troubleshooting
11/21
Post-Testing & Last-Minute Modifications
12/05
Figure 3: Gantt Chart of Project Deliverables and Major Milestones
A ug 31
Sep 7
Sep 14
Sep 21
Sep 28
Oct 5
Oct 12
Oct 19
Oct 26
No v 2
Temperature Senso r & Valves
Research
M icro co ntro ller Research
Test, Evaluate, & Select
Co mpo nents
P urchase Co mpo nents/Wait fo r
Delivery
Design: System Co mmunicatio n
Circuits
Design: Temp. Senso r Signal
A cquisitio n/Co nditio ning Circuits
Design: Valve Senso r Signal
A cquisitio n/Co nditio ning Circuits
Design: Valve Co upler, Sho wer
Head Extensio n, Temperature
Co ntro l P anel
Figure 4: Gantt Chart of Research and Design Tasks
7
Oct 5
Oct 12
Oct 19
Oct 26
A ssembly: System
Co mmunicatio n Circuits
A ssembly: Temperature Senso r
Signal A cq. & Co nd. Circuits
A ssembly: Valve Senso r Signal
A cq. & Co nd. Circuits
A ssembly: M o to r-Valve Co upler,
Sho wer Head Extensio n,
Temperature Co ntro l P anel
Develo pment: System
Co mmunicatio n SW
Develo pment: Temperature
Senso r A cquisitio n SW
Develo pment: M o to r Co ntro l SW
Develo pment: Temperature
Co ntro l SW - B asic User
Functio nality & User Interface
Figure 5: Gantt Chart of Assembly and Development Tasks
Oct 10
Oct 17
Oct 24
Oct 31
No v 7
No v 14
No v 21
No v 28
Dec 5
Dec 12
Dec 19
Integratio n: System
Co mmunicatio n SW & HW
Integratio n: Temperature Senso r
SW & HW
Integratio n: Valve Senso r SW &
HW
Integratio n: M o to r Co ntro l SW &
HW
Integratio n: M o to r Co ntro l SW &
Valve Senso r SW
Test and Tro ublesho o t: Iso lated
Senso r Circuits
M echanical HW
SW
Test and Tro ublesho o t:
Integrated M o dules
P o st-Testing M o dificatio ns
Last-M inute
Testing/M o dificatio n
Figure 6: Gantt Chart of Integration and Testing Tasks
8
8. Team Organization
Tempero Systems is composed of five members, all from the Engineering Science
program at Simon Fraser University. Each member possesses a high work ethic,
excellent communication skills, and co-op experience. Additionally, each of us is on
track to graduate with an honours degree.
Our team will function with each member having defined tasks. We will divide our
project tasks into major blocks, and have sub-teams of two or three people complete each
block. One of our goals is to keep other team members abreast to each part of the project
by keeping extensive documentation as progress is made. The documentation will
include everything from parts used, diagrams, and references, to general explanation of
their design choices. With each team member knowledgeable on each part of the project,
sub-teams can easily seek help from other sub-teams.
To ensure a high level of productivity, the Tempero Systems members will generally
work on tasks that suit their strengths, or areas in which they are comfortable. However,
team members are encouraged to stray away from their forte to learn new things and to
expand their skill set. Within Tempero Systems, Mr. Merin, Ms. Ni, and Mr. Tai are
more skilled in software, whereas Mr. Au-Yeung, and Mr. Wong are more skilled in
hardware.
A key theme throughout the coordination of our team is efficiency. Our members have
other commitments; therefore, we would like to limit the amount of hours devoted to the
project. For example, the extensive documentation described above, although tedious,
will decrease the amount of time spent composing other documents, and keep other team
members informed.
We hold meetings in the frequency of three meetings for every 2 weeks, which works out
to a meeting every 4-5 days. Jason Wong coordinates and documents the meetings,
which are to be under one hour in length. Prior to meetings, members are required to
submit progress reports since the last meeting. As a result, we can concentrate on
problem solving, and discussing issues to further our progress.
In addition to the group members, Tempero Systems is also working closely with other
knowledgeable people within the School of Engineering Science at Simon Fraser
University.
9. Company Profile
Stephen Au-Yeung, Vice President of Operations
Stephen Au-Yeung is a fourth year electronics engineering student at Simon
Fraser University. His main interests are circuit design and software
programming. Some of his previous experiences include taking part in the
building process of the new sonar system in the Simon Fraser University
9
Underwater Research Lab (URL) with Dr. John Bird. He also has exposure to FPGA
programming and communication systems. In addition, Stephen has shown strong
communication and team management skills, which are important assets for the
prosperity of Tempero Systems.
Francis Merin, Vice President of Quality Assurance
Francis Merin is a fourth year electronics engineering student at Simon Fraser
University with interests in telecommunications and signal processing. He
completed a research work term with Dr. Shahram Payandeh working on an
imaging application for a micromanipulation system. In addition, he has
recently completed a work term with Polycom Canada Ltd. where he worked
as a test engineer performing audio quality testing of Voice over IP telephones. Francis’s
software skills include applications and systems programming using Java, C/C++, and
MFC. Francis is a methodical individual whose communication and technical skills will
be assets in assuring the overall quality of the TemperSure System.
Linda Ni, Vice President of Marketing
Linda Ni is a fourth year electronics engineering student at Simon Fraser
University. She has developed great interests and abilities in exploring
business management and marketing along with her engineering studies.
When Linda attended National Tsing-hwa University, she was elected as the
vice-president of the Alumna of Taipei Municipal First Girls’ High. She
acquired excellent public relations skills while generating awareness of the organization
within post secondary institutes. Moreover, Linda previously worked on an awardwinning business plan project and received training for a business communication
certificate at the Vancouver Technology Institute. Such experiences grant her a wealth of
techniques in new venture marketing. As the Vice President of Marketing of Tempero
Systems, Linda is responsible for market research, corporate identity and driving an
integrated communication strategy.
Victor Tai, Chief Technology Officer
Victor Tai is a Computer Engineering student in his fourth year at Simon
Fraser University. He has experience in various software programming
languages such as C/C++ and Java. Victor has recently completed a work
term at the Underwater Research Lab (URL) at Simon Fraser University.
During this work term, he has assisted Dr. John Bird in building a new
transmitter and repairing an old sonar system. This work term has given Victor exposure
to VHDL/FPGA design and Windows programming. With his technical expertise and
team management skills, Victor will be an asset to Tempero Systems.
Jason Wong, Chief Executive Officer
Jason Wong is a fourth year electronics engineering student at Simon Fraser
University. He has recently completed a research work term with Dr. Rodney
Vaughan where he gained experience with technical writing and self-directed
research. He has extensive experience taking a project from electronic
schematic to completion, which includes, designing PCBs and cases. Jason’s
10
software skills include real-time embedded systems, Java, C++, MFC, and assembly.
Jason will use his excellent people skills, researched the methods of being a leader,
running a team, and managing people, to assure the success of Tempero Systems.
10. Conclusion
Burns caused by hot water have been one of the many small, but potentially deadly,
dangers people face. Taking a bath or a shower is an event that many people believe to
be safe. However, statistics indicate that many injuries occur, especially to children,
because of human error. Tempero Systems is committed to developing a product to help
eliminate accidental scalding. By applying our technical expertise, our TemperSure
system will be beneficial to users of all ages by eliminating the chance of human error.
The TemperSure system is a simple, yet effective system designed by our dedicated team
members that accommodates different users with their own tastes and comforts. As an
advantage in commercialization, the two main modules of the system can appeal to
different price points, therefore effectively expanding the target market.
The proposed Gantt chart and milestone timeline presents our plan for research and
development within the project timeframe. With our proposed budget, sources of
information, and dedicated team members, we are confident TemperSure will be a
success.
11
11. References
[1] American Society of Sanitary Engineering. 1996. ASSE Standard #1016-1996
Performance Requirements for Individual Thermostatic, Pressure Balancing, and
Combination Pressure Balancing and Thermostatic Control Valves for Individual Fixture
Fittings. 19 Sept. 2004
<http://www.asse-plumbing.org/productperformancestandards.html#1016>.
[2] American Society of Sanitary Engineering. 2004. ASSE Standard #1070-2004
Performance Requirements for Water Temperature Limiting Devices.19 Sept. 2004
< http://www.asse-plumbing.org/productperformancestandards.html#1070>.
[3] Contractor magazine. 2003. Scalding water found in 91% of hotel rooms. 20 Sept.
2004 <http://www.contractormag.com/articles/newsarticle.cfm?newsid=476>.
[4] Health Canada. 27 July 2000. Injuries Associated with Tap Water - CHIRPP Injury
Reports - Injury Section, Health Surveillance & Epidemiology Division - PPHB - Health
Canada. 15 Sept. 2004 <http://www.hc-sc.gc.ca/pphb-dgspsp/injury-bles/chirpp/injreprapbles/tapwatr_e.html>.
[5] Ondine. Ondine Electronic Shower System. 19 Sept. 2004
< http://www.interbath.com/ess.html>.
[6] Powers, a division of Watts Water Technologies, Inc. 1 May 2004. Scalding Water
Found in Over 92% of Hotel Rooms Surveyed…Legionella also a Risk. 14 Sept. 2004
<http://www.powerscontrols.com/pdf-files/news/HotelRooms_Surveyed.pdf>.
[7] Powers, a division of Watts Water Technologies, Inc. 2004. Special Report: Shower
valve safety concerns on the rise. 14 Sept. 2004 <http://www.powerscontrols.com/pdffiles/hotdownloads/SHOWER_SAFETY-Special_Report.pdf>.
12

Tempero Systems Inc. Proposal for a Shower Temperature Control

Transcription

Similar documents

9718 Aquael - Acri-tec

GW 031B - GULIWER Electronics

GW 031A - GULIWER Electronics

VANNAS ISTABA VISINTĪMĀKĀ VISBĪSTAMĀKĀ

Stork poem baby shower invitation

moor street, rainham

Baby Shower Poem - Play.Party.Plan

FOOT WASH STATION with MISTING UNIT IN STAINLESS STEEL