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TunnelWatch: Its Effect on Operating Expenses Based on a Real Installation
CONTENTS
1.0 Introduction
2.0 Overall Description of Carwash
3.0 Description of Tunnel and Associated
Equipment
3.1 Prewash Preparation
Area
3.2 Tunnel Equipment
3.3 Equipment Room
4.0 Overview of Cost Areas
5.0 Analysis
5.1 Services vs. Tunnel Stations
5.1.1 Overview
5.1.2 Data
5.1.3 Analysis
5.1.4 Conclusion
5.2 Electrical Usage
5.2.1 Overview
5.2.2 Data
5.2.3 Analysis
5.2.4 Conclusion
5.3 Water Usage
5.3.1 Overview
5.3.2 Data
5.3.3 Analysis
5.3.4 Conclusion
5.4 Chemical Usage
5.4.1 Overview
5.4.2 Data
5.4.3 Analysis
5.4.4 Conclusion
6.0 Cost per Tunnel Inch
7.0 TunnelWatch Application
8.0 Savings Summary
9.0 Conclusions
1.0 Introduction
This report describes an analysis of the operation of a typical carwash
facility before and after installation of DRB Systems, Inc.'s TunnelWatch
control system. The intent was to determine the cost advantages
of the precise and flexible control provided by TunnelWatch as
compared to a conveyor pulse
driven system. The facility chosen represents a better than normal
installation, since the pulse spacing is 2 to 3 times as precise
as is normal (8.7inches
vs. 1 to 2 feet), and the controller to be replaced is a microprocessor-based
system. The methodology used was to establish a cost model based
on the operation during the three to six months prior to TW installation,
and then
monitor and compare costs for a period immediately following the
installation.
During installation, certain TW features were incorporated which cannot be analyzed, such as collision prevention. These features are noted for completeness.
2.0 Overall Description of Carwash
The carwash used as the basis for this study is located near Akron, Ohio. All costs used in the analysis reflect local rates. The wash is a privately-owned, full-service wash with an average volume of 1000 washes per week. The wash consists of four areas: an outside prewash preparation area, the wash tunnel, a post-tunnel drying and services area (indoor), and the cashier area beside the tunnel. The side wall of the tunnel facing the cashier area is windowed to allow customer observation of the wash process.
As a customer approaches the entrance, a salesperson takes the order for desired services and gives a sales ticket to the customer, who then exits the car and goes inside the building to pay and await the finished car.
The order for desired services is entered into the tunnel control system by the salesperson. The car is driven to the conveyor start position, where, assuming selection of a full service wash, two persons manually spray the outside of the car, the wheels/tires, and the removed floor mats. The car interior is vacuumed and the windshield inside is wiped. This area is the Prewash Preparation Area. Within this area are:
- Two pressure guns which spray the car exterior
- Two pressure guns which spray the wheels
- One pressure gun which sprays the car front
- One pressure gun which sprays the removed floor mats
- Two large vacuum hoses used to clean the car interior
Upon completion of these tasks, the next roller to arrive on the conveyor is triggered by foot pedal to start the car into the tunnel.
When the car emerges from the exit of the tunnel, it is driven to a spot in a large room dedicated to manual towel drying, touch-up spot cleaning, and performance of additional services as required. Upon completion the customer then drives out the exit door.
3.0 Description of Tunnel and Associated Equipment
The following is a descriptive list of all major equipment associated with the actual operation of the tunnel. Not listed are the towel washing and drying machines, the portable vacuum cleaners used in the manual services, the TV security system, and any other similar miscellaneous equipment not directly tunnel-related.
3.1 Prewash preparation area
Pressure Guns - Vehicle Exterior
Type - Manual, high pressure guns (qty 2)
Chemical - Detergent + water
Pressure Guns - Whitewall Tires
Type - Manual, city water pressure (qty 2)
Chemical - Wheel cleaner + water
Pressure Gun - Bug Spray
Type - Manual, city water pressure
Chemical - Bug solvent + water
Pressure Gun - Floor Mats
Type - Manual, high pressure gun
Chemical - Water only
Vacuum Hose - Vehicle Interior
Type - Large vacuum cleaner hose/nozzle (qty 2)
3.2 Tunnel equipment
Conveyor
Total length - 120ft.
Usable length - 116ft.
Roller spacing - 52in.
Conveyor speed - 9.3ips, or 0.775fps
Pulse spacing - roller spacing/6, or 8.667in.
Roller start - manual, foot pedal
Motor - hydraulic
Enter Switch
Type - magnetic loop in floor
Size - 4ft 6in long
Location - center is 20ft from roller start
Distance from REF - The enter switch center is REF
Presoak Arch
Type - simple arch with spray nozzles
Control - controller cycled
Chemical - PRESOAK I (Grace-Lee) + water
Pressure - city water pressure
Distance from REF - 4ft 6in
Length - 4in
Wheel Spray Station
Type - two successive wheel-operated pinch valves
Control - none, wheel weight actuation
Spacing - 35in between spray positions
Chemical - Bright 45
Pressure - city water pressure
Distance from REF - 6ft 5in
Length - 35in
Soak I Station
Type - large, articulating mitter + wheel brushes
Control - controller cycled
Length - 10ft 8in
Chemical - Cling & Clean (Grace-Lee) + water
Pressure - city water pressure
Motors - Mitter = 13/4hp elect, Wheel brushes = hydraulic
Distance from REF - 13ft
Length - 10ft 8in
Foam Arch
Type - simple arch with spray nozzles
Control - controller cycled
Chemical - Cling & Clean + water
Distance from REF - 24ft 1in
Length - 4in
Soak II Station
Type - mitter + lower detail brushes
Control - controller cycled
Chemical - Cling & Clean + water
Pressure - city water pressure
Motors - Mitter = 13/4hp elect, Detail brushes = hydraulic
Distance from REF - 25ft 10in
Length - 7ft 3in
Chassis Rinse Station
Type - simple array of nozzles beneath vehicle
Location - under Soak II station
Control - controller cycled
Chemical - plain water
Pressure - city water pressure
Distance from REF - 24ft 10in
Length - 3ft
Side Brushes
Type - vertical rotating cloth brushes w/detergent injection
Control - controller cycled
Chemical - Cling & Clean + water
Pressure - city water pressure
Motors - 11/2hp electric, top mounted (qty 2)
Distance from REF - 36ft
Length - 3ft
Polish Wax Arch
Type - arch with spray nozzles + mitter
Control - controller cycled
Chemical - Ultra Shine Clear Coat (Grace-Lee) + water
Pressure - city water pressure
Motor - 11/2hp electric
Distance from REF - 53ft
Length - 3ft 9in
Rinse Station
Type arch with spray nozzles + Washtron X-100 spray arch
Control - controller cycled
Chemical - Prep Rinse or Cold Wax (Grace-Lee) + water
Pressure - high pressure pump, Sherman 3416A
Distance from REF - 57ft 9in
Length - 8ft 4in
Chassis Rust Inhibitor Station
Type - simple array of nozzles beneath vehicle
Location - under X-100 spray arch
Control - controller cycled
Chemical - Rust Inhibitor + water
Pressure - city water pressure
Distance from REF - 56ft 11in
Length - 2ft
Dryer Station
Type - 2 side blowers, contour follower top blower
Control - controller cycled
Chemical - none
Motors - 20 hp 230V 3ph electric (qty 3)
Distance from REF - 75ft 4in
Length - 5ft from side blower to top blower
3.3 Equipment Room
Electric Motors
Hydraulic Pump - 7.5hp 230V 3ph 20.4 A/ph (qty 2)
Rinse Pump – 15 hp 230V 3ph 40A/ph (qty 2, only 1 used)
Prewash Preparation Pump - 7.5 hp 230V 3ph 22.2 A/ph (qty 2)
Air compressor (for chemical pumps) – 5 hp 230V 3ph 15 A/ph
Vacuum Pump (Prewash area) - 10hp 230V 3ph 26A/ph
Controller Boxes
Main controller box, wall mounted, A-B microprocessor control (Replaced by two TunnelWatch control boxes)
Motor starter box, wall mounted
Motor starter box, wall mounted, loft (blowers, mitters)
Main power circuit breaker box, wall mounted
Chemical Dispensing Stations
Wheel spray station - 55gal drum, small electric pump (FLOJET)
Prewash whitewall guns - 30gal drum, float mix tank, FLOJET
Presoak arch - 55gal drum, FLOJET, mix valve, solenoid valve
Bug spray gun - 55gal drum, float mix tank, FLOJET (air press)
Polish wax arch - 55gal drum, float mix tank, submersible pump
Foam arch - 55gal drum, float mix tank, FLOJET
Soak I, Soak II, Side brushes - same tank as Foam, metering pump
(Liquid Metronics Inc. model B721-91S 60GPD, stroke = 30, speed, = 26)
This supplies 4 solenoids which control flow.
Rinse Station - either of two 55gal drums each with a Liquid
Metronics Inc. model A151-91S 24GPD metering pump, depending on
service - normal wash set at stroke = 70, speed = 90, optional
wax set at stroke = 70, speed = 90, feeding the mixing tank of a
Sherman 3416A 15hp pump, where it is mixed with water
Rust Inhibitor - 10gal tank, A151-91S pump set at stroke = 20,
speed = 59, mix valve, solenoid water valve
Prewash Guns - 55gal drum concentrate, pump to 55gal mix tank,
feeds 7.5 hp pressure pump
Floor Mats Gun - city water to 7.5 hp pressure pump
4.0 Overview of Cost Areas
The cost of running the wash can be broken into six basic categories:
- Facility
- Supervision/Administrative
- Labor
- Electrical Usage
- Water/Sewer Usage
- Chemical Usage
Facility includes the building, the equipment, maintenance, taxes, licenses, insurance, etc. These costs are not dependent upon wash volume in general and are not part of this analysis.
Supervision and administrative costs are likewise not directly related to wash volume and are not part of this analysis.
Labor costs are complex and are not always directly proportional to tunnel traffic, since several manual extra services are sold, such as special cleanup, tar removal, hand polishing, vinyl top care, total interior cleaning, etc. The labor costs are not part of this analysis.
The last three categories are related to the number of washes performed and are the subject of this analysis. Separate analyses were made of each category, based on data obtained from the operator, observations and measurements made onsite, and where data is sparse or not available, estimates of usage.
5.0 Analysis
5.1 Services vs. Tunnel Stations
5.1.1 Overview
The following are the services or service packages that the customer can choose. Each is described in terms of the tunnel station operations used to provide that service.
Exterior
This is the minimum wash service. No Prewash interior preparation is provided, so the vacuum and floor mat operations are not done. Tunnel stations used are: presoak, wheel spray, soak I, foam, soak II, side brushes, rinse station with normal metering, and dryer.
Full Service
This is the basic wash service. Same as exterior except includes vacuum and floormat interior services.
Tunnel stations are the same.
Super Wash
This is the same as the Full Service, plus tunnel stations chassis rinse and chassis rust inhibitor are used, and
the rinse station uses the optional wax.
Weatherbeater
This is the same as the Super Wash plus the polish wax arch is used.
The Works
This is the same as the Weatherbeater except several manual services are added: air freshener, wheel-brite (uses gun spray white wall cleaner), and hand scrub white wall tires.
Add-ons
The various individual components can be purchased as add-ons to the Exterior or Full Service washes. Thus, chassis bath with rust inhibitor, the optional rinse sealer setting, and the polish wax can be specified separately.
5.1.2 Data
The following data was obtained from the operator's CarWatchTM system sales reports for the five months preceding TW installation and for a six week period after installation.
| PERIOD |
TOTAL
WASHES |
SUPER
WASH |
WEATHR
BEATER
|
THE
WORKS |
Chass
Bath |
Polish
Wax |
Sealer
Wax |
| 6/8-7/8 |
4125 |
120 |
496 |
369 |
141 |
175 |
154 |
| 7/8-8/6 |
2880 |
85 |
351 |
301 |
111 |
139 |
64 |
| 8/6-9/4 |
3697 |
156 |
456 |
371 |
136 |
178 |
108 |
| 9/4-10/6 |
4618 |
175 |
591 |
523 |
164 |
236 |
68 |
| 10/6-11/5 |
3811 |
137 |
495 |
394 |
146 |
169 |
57 |
| 2/3-3/12 |
6454 |
368 |
1090 |
502 |
1431 |
63 |
26 |
| Totals |
25585 |
1041 |
3479 |
2460 |
2129 |
960 |
477 |
5.1.3 Analysis
Analysis of the sales data, using the tunnel station operation vs. service information listed shows that of the 25585 washes:
9109, or 35.6%, used the chassis bath/rust inhibitor
7457, or 29.2%, used the sealer wax
6899, or 26.9%, used the polish wax
Spot checks showed that the above percentages are consistent on a week-by-week
basis as well as on a month-by-month basis except,
as in the last (post-installation) time period, when
there has been a long period of heavy snowfall which
tends to sell more rust inhibitor and less polish wax.
This means that at this wash, each of the special tunnel
services is applied at a fairly
constant rate of about 30% of the total washes. Therefore,
the usage of the associated water and chemicals is
directly proportional to total
washes.
5.1.4 Conclusion
The usage of water and chemicals to deliver the optional tunnel services can be considered a constant 30% of that used for the remaining tunnel stations. However, a larger variable is the tendency of the wash owner to repeatedly adjust the chemical types and flow rates to balance operating cost vs. perceived wash quality.
5.2 Electrical Usage
5.2.1 Overview
The major consumers of electrical power in the tunnel are the various motors used to move the mitters and brushes, provide chemical mix pressure spray, provide hydraulic pressure to drive the conveyor and wheel and detail brushes, and to blow the air at the dryer station. All other electrical loads are minor in comparison. These include the metering pumps (1 to 2 amperes @115VAC, intermittent duty), the solenoids (similar load to the metering pumps), and the controller boxes. As a result, the analysis concentrated on the motor draws and duty cycles, with special emphasis on the blower motors at the dryer station (the largest single consumer).
5.2.2 Data
5.2.2.1 Electric bills
| PERIOD |
KWH |
BILL - $ |
Total
Washes |
Gross
cost/wash |
| 4/7- 5/7 |
9440 |
717.32 |
- |
- |
| 5/7 - 6/8 |
11120 |
775.14 |
- |
- |
| 6/8 - 7/8 |
11600 |
727.93 |
4125 |
$0.1765 |
| 7/8 - 8/6 |
9120 |
636.13 |
2880 |
$0.2209 |
| 8/6 - 9/4 |
10000 |
718.84 |
3697 |
$0.1944 |
| 9/4 - 10/6 |
11120 |
761.62 |
4618 |
$0.1649 |
| 2/3 - 3/12 |
8880 |
606.21 |
6454 |
$0.0939 |
| (Post-TW)
Totals |
71280 |
4943.19 |
N/A |
N/A |
The average cost per KWH is $0.0695.
Demand Billing
The demand meter portion of the electric meter used by the utility companies in this area includes a thermal heating element which spreads the demand "window" over a time period of 15 minutes to 1 hour. Peak demands of the duration seen during a motor startup are integrated over the time window and do not add significantly unless prolonged or repeated often. The demand at this site averaged 0.8 as read on the meter.
5.2.2.2 Major Electrical Consumers
Tunnel Equipment
Hydraulic Pump (Brushes) - 7.5hp 230V 3phase 20.4A/ph
Mitter motor (Soak I) - 13/4hp 230V 3ph 6A/ph
Mitter motor (Soak II) - 13/4hp 230V 3ph 6A/ph
Side brush motor – 1 1/2 hp 230V 3ph 5 A/ph (qty 2)
Mittermotorpolish)-1 1/2 hp 230V3ph 5 A/ph
RinsePressurePump-15 hp 230V 3ph 40 A/ph
Dryer blower motors -20 hp 230V 3ph 60 A/ph (qty 3)
Hydraulic Pump (Conveyor)- 7.5 hp 230V 3ph 20.4 A/ph
Air Compressor (for chemical pumps) - 5hp 230V 3ph 15A/ph
Misc. solenoids, pumps, controllers - 2000W
Prewash Preparation Equipment
Vacuum Pump (Prewash area) - 10hp 230V 3ph 26 A/ph
Prewash Preparation Pump - 7.5 hp230V 3ph 22.2 A/ph (qty 2)
Non wash-related
Towel washers/dryers
Facility lighting
Air conditioning
Misc. - manual services, security, etc.
No analysis was done on non wash-related usage.
5.2.3 Analysis
The analysis of the electrical usage will consider first, the tunnel equipment, then the conveyor, and finally the prewash preparation equipment. Since the dryer blower motors are the largest users, a further study was made to determine if their duty cycle could be reduced by using the increased control capability of TunnelWatch.
Tunnel Equipment
The following is a table showing electrical usage per electrical consumer, calculated on a per-wash basis:
| CONSUMER |
VA/ph |
VA Total |
W(0.8PF) |
Hour/Wash |
KWH/Wash |
| Hyd-Brush |
4692 |
8127 |
6501 |
0.0217 |
0.141 |
| Mitter I |
1380 |
2390 |
1912 |
0.0115 |
0.022 |
| Mitter II |
1380 |
2390 |
1912 |
0.0102 |
0.020 |
| Side Brsh |
2300 |
3984 |
3187 |
0.0091 |
0.029 |
| Mitter P |
1150 |
1992 |
1594 |
0.0088 |
0.014 |
| Rinse Pmp |
10350 |
17927 |
14342 |
0.0104 |
0.149 |
| Dryer |
41400 |
71707 |
57366 |
0.0094 |
0.539 |
| Air Comp |
3450 |
5975 |
4780 |
0.0088 |
0.042 |
| Misc |
- |
- |
2000 (est) |
0.0088 |
0.018 |
| - |
- |
- |
- |
Total KWH
|
0.974 |
Conveyor hydraulic pump - 6501Watts
Prior to installation of TW, the conveyor usage was not directly related to the number of washes delivered since it could be left running during non-wash time and could be shut off manually at any time. On-site
observation showed it was on approximately 90% of the time. Since the tunnel is open 9 hours per day, 7 days per week (total 63hours), the conveyor was on about 57hours per week. At an average of 1000 washes per week, the conveyor usage was 0.057 hours per wash. At 6.501 KW for 0.057hr, the conveyor usage of electricity was 0.371KWH per wash.
TW control of the conveyor assures that the usage is limited to the time that vehicles are actually in the tunnel. During periods of inactivity, the conveyor is always off. The potential savings are obvious and are in the range of 40% to 50%.
Prewash Preparation Equipment
| CONSUMER |
VA/ph |
VA Total |
W(0.8PF) |
Hour/Wash |
KWH/Wash |
| Pres Guns |
5106 |
8844 |
7075 |
0.0083 |
0.059 |
| Pres WSW |
5106 |
8844 |
7075 |
0.0020 |
0.014 |
| Vacuum |
6440 |
11154 |
8923 |
0.0200 |
0.179 |
| - |
- |
- |
- |
Total KWH |
0.252 |
This equipment is all manually operated and not controllable
by TW. No savings in this area are forecast.
Dryer Duty Cycle
As is shown in the analysis of tunnel equipment usage, the
dryer blower motors are responsible for more than half of the power consumption. Therefore, it was decided that further study was indicated to see if the dryer cycle could be optimized.
The dryer station contains two linked, but separate drying operations. Two motors provide airflow to two side blowers which dry the sides of the car. A third motor provides airflow to a contour-following top blower which dries the car top. The side blowers are encountered by the car 5 feet ahead of the top blower. In this tunnel, the side and the top blowers were cycled together. This required the blower cycle be the sum of the car transit time plus the time to travel the 5 foot blower separation, plus any other allowance built into the controller. An obvious advantage would be obtained if the controller could handle the two drying operations separately. TunnelWatch can do this easily.
To determine the actual dryer cycle under working conditions, the cycle
was timed, from turn on to turnoff, for a variety of cars to assess the
potential savings in this area. The following table shows those measurements
as well as the calculated real car transit time (based on the conveyor
speed of 0.775fps) and the difference between the two.
TYPE OF CAR
YR MAKE/MODEL |
Length-
feet |
Dryer On
Time-sec |
Conveyor
Time-sec |
Excess
On time |
| 91 Plymouth Acclaim |
15.1 |
32.8 |
19.5 |
13.3 |
| 87 Oldsmobile 98 |
16.4 |
35.0 |
21.2 |
13.8 |
| 87 Ford Escort |
14.8 |
30.5 |
19.0 |
11.5 |
| 92 Cutlass Supreme |
16.0 |
33.8 |
20.7 |
13.1 |
| 91 Dodge Dynasty |
16.2 |
33.6 |
20.9 |
12.7 |
| 92 Nissan Maxima |
15.7 |
35.0 |
20.2 |
14.8 |
| 92 Honda Civic VX |
14.4 |
30.5 |
18.6 |
11.9 |
| 88 Dodge Daytona ES |
14.9 |
32.8 |
19.3 |
13.5 |
| 88 Buick Le Sabre Ltd |
16.4 |
35.2 |
21.1 |
14.1 |
| 86 Chevy Monte Carlo |
16.7 |
35.9 |
21.5 |
14.4 |
| 85 Merc Grand Marquis |
17.9 |
36.2 |
23.1 |
13.1 |
| Averages |
15.9 |
33.8 |
20.5 |
13.3 |
The measured dryer cycle time exceeds the car transit
time by an average of 13.3 seconds. If the fixed dryer displacement of
5 feet (6.5 seconds) is subtracted, an average of 6.8 seconds of cycle
time is wasted. This time is in the present system for three basic reasons:
- Conveyor pulse resolution - this is 8.7 inches or 0.9 seconds.
- Allowance for motor spin-up, car lead, and car follow is about 4.6 seconds or 3.6 feet of conveyor travel. Observation shows that most is follow time - after the car passes.
- Enter switch sensor uncertainty - this appears to be about 1.3 seconds, or 1 foot of conveyor travel.
TunnelWatch controller capacity and flexibility eliminates the 5 foot waste of cycle time by providing separate and independent control of the top and side blowers. The "to-the-inch" control inherent in TW eliminates the conveyor pulse resolution variation allowance and also allows drastic reduction or elimination of the spin-up, car lead, and car follow allowances, since they were originally provided because of poor control accuracy.
Allowing 2 seconds of cycle time for motor spin-up, TW reduced the average cycle time by 11.3 seconds. At an operating usage of 0.016 KWH per second of blower operation, this would result in a savings of 0.18KWH, or 1.3 cents per wash.
TunnelWatch offers two other features which can be used to control motor usage: Staggered starts and Look-ahead.
Staggered starts are used to reduce the initial line voltage slump resulting from massive motor start inrush current transients by insuring that no more than one large motor starts at a time. In some billing areas this could reduce the demand billing if the thermal device is of short time, constant, or nonexistent in the electric meter.
Look-ahead is the ability to determine, from the traffic on the conveyor, that large motors at the wash stations would be better left running rather than being turned off and then immediately turned back on. This feature has three positive effects:
- It reduces acceleration-induced equipment wear and tear
- It reduces noise transients from startups
- It reduces electrical inrush cycles
Of the three, the electrical inrush reduction is the most significant. The inrush currents associated with motor startup are, on the average, 6 times the running current. At a running current of 60 amperes per phase for the 20hp dryer motors, inrush currents are about 360 amperes per phase for each motor. While these currents do no harm to the motors, they can cause arcing and burnout of controller contacts. Since the single most frequent cause of 3 phase motor failure and burnout is "single phasing" (which simply means that one of the three power phases has been interrupted), failure of a controller contact can result in the loss of a very expensive motor.
To a minor extent, Look-ahead will affect electrical usage. The analysis, if done accurately, is complex. A simplified explanation is that if the inrush current used to start the motor was spread out over sufficient time to bring its value
down to that of the running current, then the electrical usage would be the same. The amount of time would, on the average, be 3 times the startup time. Since startup time is 1 to 2 seconds on a large, loaded
motor, the break-even point where the cost is the same in electrical usage for either remaining running or performing the shutdown-turn-on cycle is 3 to 6 seconds. This
corresponds to conveyor traffic spaced from 2.5 to 5 feet apart, which occurs often on a very busy day.
With any system,
more accurate enter switch sensing will result in less wasted
allowance. This system uses
a large magnetic loop which, while reliable, has uncertainty.
This will be changed to an IR "eye" sensor with a 3 inch
uncertainty.
5.2.4 Conclusion
The baseline system consumes electrical power as follows:
| Tunnel system less conveyor ------------ |
0.974 KWH/wash |
| Conveyor system ----------------------- |
0.371 KWH/wash |
| Total tunnel - |
1.345 KWH/wash |
At 6.95 cents per KWH, the cost is 9.35 cents per wash.
Installation of TunnelWatch, along with the modified dryer
cycle, a controlled conveyor start, and reduction/elimination
of lead/follow allowances will result in the following savings:
| Dryer cycle ------------------------------- |
1.3 cents/wash |
| Conveyor start --------------------------- |
2.2 cents/wash |
| Tighter control through tunnel ---------- |
1.0 cents/wash |
| Total savings on electrical usage - |
4.5 cents/wash |
At 4000 washes per month, the savings potential is $180 per
month on the electric bill. The after - installation sample
showed a savings
amounting to 49% of the electric bill for that period, which
verifies the analysis.
5.3 Water Usage
5.3.1 Overview
In most areas, water usage is the direct determiner of both the water bill and the sewer bill. The sewer bill is usually based upon the water usage, multiplied by a constant factor. Since water usage is high at a car wash, and, in many areas water is a dear and costly commodity, an analysis is indicated.
The baseline car wash has had a variable configuration during the study period. Two Washtron X-100 rinse arches are physically installed in the tunnel. The operator experimented with the usage of both versus one and decided on one as the configuration to be used. The second X-100 would be removed and moved to a second wash owned by the same operator. As a result of this experimentation, the water bills are not consistent nor are they directly related to wash traffic, because the X-100 is a high pressure system which is a heavy water user. Just before TW installation, the operator decided to again use the second X-100, and that is how the TW was programmed.
A second factor is that, for this study, it was not practical to interrupt the plumbing to directly measure water flow rates. Therefore, the water usage analysis is based upon best estimates.
In this area, water is plentiful and water reuse is not a normal consideration. In many areas, water conservation rules demand water recycling systems. The analysis of that type of system, while different, would show reduced costs because the water volume per wash would be decreased due to more accurate control. This would reduce recycling costs as well as water and sewer bills.
5.3.2 Data
| PERIOD |
USAGE (000) Gal |
COMMENTS |
| 3/17 - 4/17 |
286 |
X-100 Operating |
| 4/17 - 5/17 |
213 |
|
| 5/17 - 6/17 |
185 |
X-100 Disabled |
| 6/17 - 7/17 |
116 |
|
| 7/17 - 8/18 |
127 |
|
| 8/18 - 9/17 |
233 |
|
Cost per thousand gallons, including sewers = $5.32
5.3.3 Analysis
The data, though somewhat uneven because of the X-100 usage, does allow a reasonable estimate of the water usage of one X-100 arch. That estimate is about 30,000 gallons for a
nominal month (4000 washes). Following is our best estimate of per month
water usage in each area of the wash:
| AREA |
USAGE (000) |
| Prewash Preparation area - all pressure guns |
30 |
| All Tunnel arches except X-100 |
35
|
| Washtron X-100 Rinse arch |
30 |
| Total Wash Traffic-related: |
95 |
| Towel Washing Machines |
10 |
| Hose-downs of floor, equipment |
6 |
| Toilets, sinks |
4 |
| Other / Misc. |
2 |
| Total Car Wash nominal usage: |
117 |
The costs per wash, considering the wash traffic-related usage only, assuming
4000 washes per month, are:
Prewash Preparation area:
- 30,000 gallons per month
- Divide by 4000 = 7.5gallons per wash
- At $5.32 per thousand gallons, = 4 cents per wash
Tunnel area:
- 65,000 gallons per month
- Divide by 4000 = 16.25 gallons per wash
- At $5.32 per thousand gallons, = 8.65 cents per wash
5.3.4 Conclusion
The water/sewer costs within the tunnel are quite dependent upon the
type of arches installed, as well as the operator selected flow rates,
pressures and cycles. For the baseline wash, the tunnel water/sewer usage
cost was 8.65 cents per wash.
Installation of TunnelWatch, with its more accurate control, allows
a 20% reduction of cycle time per wash at each arch, based
on the dryer motor cycle analysis. This would save 1.73 cents
per wash, or, at 4000
washes per month, $69.20 savings per month. Post TW installation
data taken for the period of 2/3 through 3/12 shows a usage
of 282,600 gallons,
or 223,100 gallons for a one month period. This includes
the additional X-100 arch plus numerous hose-downs due to
accumulation of road salt,
etc. because of unusually snowy weather. Therefore, it can
be concluded that any water savings were masked. In view
of the variability of the
operator water and chemical mixes and flow settings, it was
not possible to establish or maintain a consistent basis
for measuring the per wash
usage or savings due to TW control.
5.4 Chemical Usage
5.4.1 Overview
The operator buys chemicals in either 55 or 30 gallon plastic drums
or in powder form which is subsequently mixed with
water in a 55 gallon drum. All drums are straight-sided
and translucent, so the chemical
level can be observed and monitored. By simply
computing the volume per inch of each container
type, the chemical usage can be measured
fairly accurately. The operator marks each drum
and measures usage frequently. Mix ratios are often
changed to compensate for weather/season,
perceived wash quality, supplier/brand changes,
and cost per wash. This dynamic mixture modification
makes accurate measurement and analysis
difficult, so the analysis will be done on an average
usage basis.
5.4.2 Data
| PERIOD |
Presoak
IN GAL |
Rinse
IN GAL |
Dry Agnt
IN GAL |
WSW Clnr
IN GAL |
Total
Washes |
| 8/27- 9/8 |
1.50 2.5 |
5.75 9.6 |
3.50 5.8 |
64 106.7 |
1274 |
| 9/8- 9/22 |
1.50 2.5 |
4.75 7.9 |
2.25 3.8 |
90 150.0 |
1655 |
| 9/22- 9/28 |
0.75 1.3 |
2.25 3.8 |
2.75 4.6 |
56 93.3 |
882 |
| 9/28-10/15 |
2.50 4.2 |
7.0 11.7 |
9.0 15.0 |
144 24.0 |
2761 |
| 10/15-10/19 |
0.75 1.3 |
0.75 1.3 |
1.75 2.9 |
27 45.0 |
463 |
| 10/19-11/3 |
2.00 3.3 |
4.75 7.9 |
8.5 14.2 |
107 178.3 |
2170 |
In a 55 gallon drum of this type, 1 inch = 1.67gallon.
5.4.3 Analysis
The chemical usage on a volume per wash basis is not consistent over the study period due to the already noted X-100 variations, the change in season, and the operator adjustments. However, the operator pays careful attention to the average cost per wash of each chemical. His average per wash costs are:
| Presoak |
$0.01 |
| Rinse |
$0.02 |
| Drying Agent |
$0.04 |
| Sealer Wax* |
$0.02 |
| WSW Cleaner* |
$0.02 |
| Polish Wax* |
$0.02 |
| Rust Inhibitor* |
$0.01 |
| Total per wash |
$0.14 |
* These costs are averaged over all washes even though used only on 30% of the washes.
5.4.4 Analysis
As in the water usage, the chemical usage is shown on an average basis. The result of installing the TunnelWatch system should be similar, i.e. a 20% savings can be expected. However, operator usage variation is sufficient to mask the effect of TW control efficiency.
6.0 Cost Per Tunnel Inch
During the study, an interesting metric was suggested to get a gross measure
of overall tunnel operating costs. The metric is the "Cost-per-inch" of
tunnel conveyor travel. This cost would not include facility
labor, and fixed costs, out of tunnel costs (prewash preparation, post-tunnel
service area), but would combine all electricity, water/sewer
and chemical usage costs on a per-wash per-inch basis. These
costs are:
| Electricity |
9.35 cents |
| Water/sewer |
8.65 cents |
| Chemicals |
14.00 cents |
| Total: |
32.00 cents |
The conveyor length is 120 feet, but the actual working length of the
tunnel is 96feet, measured from the enter switch site to the
end of the active conveyor. 96 feet is equal to 1152 inches. Dividing 32
cents by
1152 inches = 0.02778 cents per inch per wash.
After TW installation this factor was reduced by 4.58 cents due to the
49% savings in electrical usage. Thus, the new factor is 32-
4.58 = 27.42 cents/1152= 0.02380 cents/inch/wash - a 14.4% reduction in
real tunnel-related operating
costs.
7.0 TunnelWatch Application
The tunnel equipment described above requires 25 separate output control
circuits and 5 input circuits to provide control of all functions at all
stations. Since each TW control box provides 16 output circuit controls,
two boxes were required. The TW boxes are connected to the TW processor
(a PC running proprietary control software). The TW processor is then connected
to the CarWatch processor to allow integrated operation.
A new version of TW will not require an additional processor if a 386 - class CarWatch processor is already installed. This will provide the TW function without the additional space and operational-requirements of an added processor.
8.0 Savings Summary
The analysis above has shown several areas of usage which will provide
savings on a continuing basis, since actual operating costs are
reduced. Not measurable,
but no less real, are savings in maintenance due to less on-time
per wash, and in administrative costs because TunnelWatch will
keep records of running
time vs. last servicing, time to next service, and several
other data needed to track the wash performance. The operating
cost savings are: (per month,
based on an average of 4000 washes per month, assuming a constant
water/chemical requirement):
| Expense Area |
Cost now |
Savings |
| Electrical Usage |
$374 |
$180 |
| Water/Sewer |
$346 |
$69 |
| Chemical Usage |
$560 |
$112 |
| Totals |
$1280 |
$361/mth |
9.0 Conclusion
The installation of TunnelWatch in a carwash which provides an average of 4000washes per month can save sufficient operating expenses to pay for the cost of the TW in approximately 21/2 years. This is in addition to all the operational benefits derived from TW. Therefore, the installation of TW is a valid, beneficial business decision.
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