Technical Specification — Paleo Treats Water Treatment System
For Drinking Water & Specialty Coffee / Beverage Application
| Field | Detail |
|---|---|
| Document Number | RO-SPEC-001 |
| Revision | Rev G — Regulatory traceability added: NSF/ANSI 61 (or ANSI-accredited equivalent) explicitly cited as a hard requirement per SD DEH; both stationary (CalCode) and mobile (MFF) permitting paths documented in §8.1 with the MFF water-tank provisions cited as the controlling design reference for either path |
| Date | 16 April 2026 |
| Application | Drinking Water Production — Specialty Coffee, Ice & Beverage Service |
| Supply Voltage | 240 VAC Single-Phase, 60 Hz (USA) |
| Intended Use | Potable Water — Sanitary Construction Required |
⚠ ALL MOTORS, DRIVES, AND ELECTRICAL COMPONENTS MUST BE RATED FOR 60 Hz OPERATION
1. System Overview
This specification defines the requirements for a compact reverse osmosis (RO) water treatment system intended for commercial drinking water production in a specialty coffee shop environment. The system serves an espresso machine (SanRemo Cafe Racer), an ice maker, and a drinking water filling station. The system shall be of full sanitary construction throughout all wetted surfaces and shall comply with applicable NSF/ANSI standards for potable water contact materials.
The system processes municipal or well feed water through sequential pre-filtration, RO membrane separation, UV disinfection, and controlled mineral re-injection to achieve a final product water profile optimised for specialty coffee extraction.
Two-Tank Architecture with UV Recirculation
The system employs a two-tank architecture with a continuous UV recirculation loop on Tank 1:
-
Tank 1 (T-101) — Buffer (15–20 gal, tall/narrow) stores raw RO permeate. Sized for peak-hourly demand bursts (ice machine + T-102 fill ≈ 10 gal worst case) with margin, not for full-day storage — RO permeate output (30–90 gph) outpaces peak demand (~10–15 gph). A recirculation pump (P-102) continuously circulates T-101 water through a UV disinfection unit and back to prevent bacterial growth during storage. Valved branches off the UV discharge provide on-demand supply to the ice machine (direct, no minerals) and to the treatment path (mineral injection → Tank 2).
-
Tank 2 (T-102) — Small buffer (5 gal) stores fully treated product water (UV-disinfected, mineral-injected) ready for distribution to the espresso machine and drinking water station.
A dedicated distribution pump (P-103) supplies pressurised product water from T-102 to the espresso machine and drinking water station.
Process Flow Diagram
FEED ──► Sediment Filter ──► Carbon Filter ──► P-101 (RO Feed) ──► RO Membrane ──► T-101
(10µm) (GAC) (CRN1S-15, VFD) (XLE Pro-2540) (15–20 gal)
│
┌─────────────────────────────────────────────────────── SV-RECIRC (N.O.) ◄───┤
│ (recirculation return) │
▼ │
T-101 ──► P-102 (Recirc/Transfer, CRN1S-4, VFD, continuous) ──► UV (40 mJ/cm²) ──┤
│
SV-ICE (N.C.) ─────┤──► Ice Machine
│ (no minerals)
SV-TREAT (N.C.) ───┘
│
Mineral Injection
(3 × metering pumps)
│
T-102
(5 gal, tall/narrow)
│
P-103 (Distribution, ½ HP VFD — TBD)
│
┌──────────┴──────────┐
Espresso Machine Drinking Water
(SanRemo Cafe Racer) Filling Station
Process Sequence
| Stage | Process Step | Primary Function |
|---|---|---|
| 1 | Sediment Pre-Filter — 4.5″ × 10″, 10-micron pleated cartridge | Remove particulates, protect downstream media |
| 2 | Carbon Block Filter — 4.5″ × 20″, GAC cartridge | Remove chlorine, chloramines, VOCs, taste & odour |
| 3 | High-Pressure RO Feed Pump (P-101) — Grundfos CRN1S-15 A-FGJ-G-E-HQQE, 60 Hz VFD-controlled | Pressurise feed water to RO operating pressure |
| 4 | RO Membrane — Filmtec XLE Pro-2540 (2540 format) | TDS / ionic reduction via semi-permeable membrane |
| 5 | Tank 1 (T-101) — RO Permeate Storage, 15–20 gal 304L/316L SS (1/2 BBL Sanke) | Buffer storage for raw RO permeate; sized for peak-burst absorption + cycle hysteresis |
| 6 | Recirculation / Transfer Pump (P-102) — Grundfos CRN1S-4 A-FGJ-A-E-HQQE (washdown), 60 Hz VFD-controlled, runs continuously | Circulate T-101 water through UV; redirect to ice machine or treatment path on demand |
| 7 | UV Disinfection Unit — Germicidal UV-C, in recirculation loop | Continuous biological disinfection of T-101 stored water |
| 8 | Post-UV Solenoid Manifold — SV-RECIRC / SV-ICE / SV-TREAT | Route UV-treated water: recirculate to T-101, supply ice machine, or send to mineral injection |
| 9 | Mineral Injection — 3 × Metering Pumps (when SV-TREAT open) | Add select minerals per active HMI recipe to control final product TDS |
| 10 | Tank 2 (T-102) — Treated Water Storage, ~ 5 gal 304L/316L SS (tall/narrow, sixtel keg) | Buffer storage for fully treated product water; fast recipe transitions |
| 11 | Distribution Pump (P-103) — ½ HP class, 60 Hz VFD-controlled (not yet procured) | Supply pressurised product water to espresso machine and drinking water |
| 12 | Points of Use | Espresso machine (SanRemo Cafe Racer), drinking water filling station |
2. Design Basis & Performance Requirements
2.1 Feed Water Conditions
| Parameter | Design Value | Notes |
|---|---|---|
| Feed Water Source | Municipal potable supply | Chlorinated; dechlorinated by carbon filter |
| Feed Pressure | 40–80 psi (2.8–5.5 bar) | Minimum 30 psi at inlet required |
| Feed Temperature | 50–77 °F (10–25 °C) | Optimum for XLE Pro-2540 element |
| Feed TDS | Up to 500 mg/L (ppm) | Design maximum; consult supplier if higher |
| SDI | < 5 (after pre-filtration) | Required per Filmtec membrane guidelines |
2.2 System Performance Targets
| Parameter | Requirement | Measurement Method |
|---|---|---|
| RO Recovery Rate | Adjustable 50–75 % (nominal 65 %) | Q_perm / Q_feed × 100 % — calculated by PLC |
| Salt / TDS Rejection | ≥ 97 % (XLE membrane rated ≥ 99 %) | (1 − C_perm / C_feed) × 100 % — displayed on HMI |
| Permeate Flow Rate | Approx. 0.5–1.5 gpm (varies with pressure & temp) | Measured by permeate flow meter (FT-102) |
| Tank 1 Capacity (T-101) | 15–20 US gallons (tall/narrow form factor) | HDPE or 304L/316L SS; NSF 61 listed |
| Tank 2 Capacity (T-102) | 5 US gallons (tall/narrow form factor) | HDPE or 304L/316L SS; NSF 61 listed |
| Product Water TDS | Programmable setpoint per HMI recipe preset | Controlled by mineral injection pumps; verified by CT-103 |
| UV Dose | ≥ 40 mJ/cm² (min. 16 mJ/cm² USEPA) | Certified UV unit in T-101 recirculation loop |
2.3 Application & Consumption Basis
The system is sized for a specialty coffee shop with the following primary equipment and daily consumption:
Espresso Machine — SanRemo Cafe Racer:
| Boiler | Volume |
|---|---|
| Pre-heating boiler | 1 L |
| Steam boiler | 8 L |
| Group head boilers (× 2) | 2 × 1 L = 2 L |
| Total machine fill volume | 11 L ≈ 2.9 US gal |
Daily Water Consumption Estimate (100 cups/day × 8 oz):
| Category | Estimate | Source Tank |
|---|---|---|
| Coffee extraction water | ~6.25 gal (800 oz) | T-102 via P-103 |
| Steam losses, hot water draws | ~1–2 gal | T-102 via P-103 |
| Backflushing / cleaning cycles | ~0.5 gal | T-102 via P-103 |
| Espresso machine subtotal | ~8–9 gal/day | T-102 |
| Drinking water filling station | ~5–10 gal/day | T-102 via P-103 |
| Total T-102 demand | ~13–19 gal/day | |
| Ice machine | ~20–40 gal/day (model dependent) | T-101 direct (via SV-ICE) |
| Total T-101 demand | ~33–59 gal/day |
Sizing rationale:
- T-102 at 5 gallons turns over 3–4× per day at typical demand (~13–19 gal/day), keeping product water fresh and enabling fast recipe transitions — a recipe change fully propagates in 1–2 fill cycles (~10–15 min) instead of most of a day. At peak draw (~1–1.25 gal/hr), 5 gallons provides 4–5 hours of buffer. The worst-case single draw is a cold fill of the Cafe Racer boilers (2.9 gal), which P-102 refills in under a minute at 4 gpm. A tall, narrow tank form factor is preferred to give adequate vertical travel for level sensing.
- Metering pump compatibility: At 4 gpm transfer rate, a 5-gallon fill takes ~75 seconds. The DDC 6-10 metering pumps (100 mL/min max) operate at 7–12% of capacity for typical recipes — well within stable dosing range. For very low dosing rates, the PLC can slow P-102 via VFD-102 during fill cycles to extend dosing time.
- T-101 at 15–20 gallons is sized for peak-hourly demand bursts, not full-day storage. RO permeate output (0.5–1.5 gpm = 30–90 gph) outpaces peak demand (~10–15 gph) by 2–6×, so the membrane never falls behind. With a useful working range of ~70% of capacity (~10–14 gal between low-start and high-stop setpoints), T-101 cycles P-101 only 3–5× per day with 7–28 minute run windows — well clear of any thrashing regime that would shorten membrane life.
- T-101 worst-case concurrent demand — ice machine fill (~5 gal) plus T-102 fill (~5 gal) firing simultaneously totals ~10 gal. A 20-gal tank handles this with ~4 gal margin; a 15.5-gal tank (1/2 BBL Sanke keg form factor) relies on the cascade interlock in §5.6 (SV-TREAT inhibited if T-101 is low) to defer T-102 fill so ice demand is always served. Both options are acceptable.
- T-101 form factor benefits — a 16" diameter × ~23" tall cylinder (custom 20-gal build) or a 1/2 BBL Sanke keg (16.125" × 23.3", 15.5 gal) gives ~250 lb less water weight on the skid vs. a 50-gal design, faster water turnover (~9–12 hr avg residence vs. ~30 hr) for fresher water even with continuous UV, and an off-the-shelf 1/2 BBL keg conversion path for cost-effective sourcing.
3. Equipment Specifications
3.1 Pre-Filtration
| Item | Specification |
|---|---|
| Sediment Filter Housing | 4.5″ × 10″ Big Blue style; 316SS or food-grade polypropylene; 150 psi rated |
| Sediment Filter Cartridge | Harmsco WB-HB-10-10W or equal; pleated polyester; 10-micron absolute; NSF/ANSI 42 listed |
| Carbon Filter Housing | 4.5″ × 20″ Big Blue style; 316SS or food-grade polypropylene; 150 psi rated |
| Carbon Filter Cartridge | Pentek GAC-20BB or equal; granular activated carbon; NSF/ANSI 42 & 61 listed; capacity ≥ 25,000 gallons |
| Connections | 1″ NPT inlet/outlet; food-grade O-rings (EPDM or NSF-grade Buna-N) |
| Pressure Rating | 150 psi working pressure minimum |
3.2 RO Membrane Assembly
| Item | Specification |
|---|---|
| Membrane Element | Filmtec XLE Pro-2540 or equal; low-energy brackish RO element |
| Format | 2540 (2.5″ diameter × 40″ length) |
| Rejection Rate | ≥ 99.0 % NaCl (manufacturer rated) |
| Permeate Flow | 50 GPD nominal at standard test conditions (77 °F, 150 psi, 250 ppm NaCl, 15 % recovery) |
| Membrane Housing | 2540 pressure vessel; fibreglass-wound or 316SS; end-port or side-port; rated ≥ 300 psi |
| O-Rings / Brine Seals | NSF/ANSI 61 compliant; EPDM food grade |
| Operating Pressure | 100–250 psi (6.9–17.2 bar) adjustable via VFD pump speed |
3.3 Product Water Storage Tanks
Tank 1 — T-101: RO Permeate Storage
| Item | Specification |
|---|---|
| Capacity | 15–20 US gallons (target 20 gal; 15.5 gal acceptable for 1/2 BBL Sanke keg form factor) |
| Form Factor | Tall, narrow — ~16" diameter × ~23" tall (1/2 BBL Sanke keg dimensions: 16.125" × 23.3") or similar aspect ratio (~1.5–2:1 H:D). Provides adequate vertical travel for high/low float switches and minimizes skid footprint and water weight. |
| Material | HDPE (NSF/ANSI 61 listed) or 304L/316L stainless steel with sanitary finish; electropolished interior preferred for display visibility |
| Purpose | Buffer storage for raw RO permeate; continuously UV-disinfected via recirculation loop; supplies ice machine directly and treatment path to T-102. Sized for peak-burst absorption + RO cycle hysteresis (3–5 cycles/day expected), not full-day storage. |
| Connections | Inlet (from RO permeate), outlet (to P-102 suction), recirculation return (from SV-RECIRC), high-level sensor port, low-level sensor port, drain, vent (with air-gap or sanitary vent cap) |
| Pressure | Atmospheric / open vented |
| Compliance | NSF/ANSI 61 certified for potable water contact |
| Sourcing path | Preferred: modified 1/2 BBL Sanke keg (304 SS, debranded, ~$80) with sanitary tri-clamp ferrules welded for 5–6 ports + electropolish. Alternative: used brewery brite tank or custom 20-gal sanitary build. See tanks. |
Tank 2 — T-102: Treated Water Storage
| Item | Specification |
|---|---|
| Capacity | 5 US gallons |
| Form Factor | Tall, narrow — ~8″ diameter × ~24″ tall (1/6 BBL Sanke keg dimensions: 9.25" × 23.3", ~3:1 aspect) to provide adequate vertical travel for continuous level sensor and to keep dead volume low at the bottom |
| Material | HDPE (NSF/ANSI 61 listed) or 304L/316L stainless steel with sanitary finish; electropolished interior preferred for display visibility |
| Purpose | Buffer storage for fully treated product water (UV-disinfected, mineral-injected) ready for distribution to espresso machine and drinking water station. Small volume chosen for fast recipe transitions (1–2 fill cycles) and high turnover (3–4×/day). |
| Level Sensing | Continuous 4–20 mA level transmitter (see §4, LT-102) — preferred over discrete float switches due to small tank height; provides proportional fill level to PLC for smarter fill control and accurate volume tracking |
| Connections | Inlet (from mineral injection manifold), outlet (to P-103 suction), level transmitter port (top-mount), drain, vent (with air-gap or sanitary vent cap) |
| Pressure | Atmospheric / open vented |
| Compliance | NSF/ANSI 61 certified for potable water contact |
| Sourcing path | Preferred: modified 1/6 BBL Sanke keg (304 SS, debranded, ~$80) with 4 sanitary tri-clamp ferrules welded + electropolish. Alternative: small custom sanitary build. See tanks. |
3.4 Pump Specifications
CRITICAL: All pump motors must be rated for 60 Hz operation. The system uses 240 V single-phase power input to VFDs which output variable-frequency 3-phase power to drive the pump motors.
Pump P-101 — RO High-Pressure Feed Pump
| Parameter | Requirement |
|---|---|
| Manufacturer / Model (procured) | Grundfos CRN1S-15 A-FGJ-G-E-HQQE |
| Pump Type | Vertical multistage centrifugal; close-coupled |
| Rated Power | Per nameplate (size VFD-101 to motor FLA; design basis was ¾ HP class) |
| Motor Type | 3-Phase induction motor; 208-230/460 VAC |
| Frequency | 60 Hz (MANDATORY — do not supply 50 Hz motor) |
| Speed | 3,450–3,500 RPM at 60 Hz |
| Full-Load Current | Per nameplate at 230 V 3-phase |
| Design Duty Point | 110 psi (253 ft head) @ 4 gpm (RO operating target; verify against pump curve) |
| Wetted Materials | 316 stainless steel impellers, diffusers & shaft; EPDM O-rings |
| Shaft Seal | HQQE mechanical seal; food-grade elastomers |
| Connections | 1-¼″ Victaulic or NPT; mating fittings to be supplied |
| Speed Control | Controlled via VFD-101 (GS21-21P0); 0–100 % speed via Modbus RTU from PLC |
| Standards | NSF/ANSI 61; CE; cULus |
Pump P-102 — Recirculation / Transfer Pump (T-101 UV Loop + Transfer to T-102 + Ice Supply)
| Parameter | Requirement |
|---|---|
| Manufacturer / Model (procured) | Grundfos CRN1S-4 A-FGJ-A-E-HQQE |
| Pump Type | Vertical multistage centrifugal; close-coupled |
| Rated Power | ½ HP (0.37 kW) @ 3,500 rpm |
| Enclosure | Washdown-rated |
| Motor Type | 3-Phase induction motor; 208-230/460 VAC |
| Frequency | 60 Hz (MANDATORY — do not supply 50 Hz motor) |
| Speed | 3,500 rpm at 60 Hz (as-rated) |
| Full-Load Current | Per nameplate at 230 V 3-phase |
| Rated performance (nameplate) | 4.84 US gpm @ 77 ft TDH |
| Design Duty Point | 30 psi (69 ft head) @ 4 gpm (system target; verify against pump curve) |
| Wetted Materials | 316 stainless steel impellers, diffusers & shaft; EPDM O-rings |
| Shaft Seal | HQQE mechanical seal; food-grade elastomers |
| Connections | 1-¼″ Victaulic or NPT; mating fittings to be supplied |
| Speed Control | Controlled via VFD-102 (GS21-20P5); 0–100 % speed via Modbus RTU from PLC |
| Standards | NSF/ANSI 61; CE; cULus |
| Operating Mode | Runs continuously. Default state: recirculates T-101 water through UV via SV-RECIRC (normally open). PLC opens SV-TREAT to fill T-102 on demand or SV-ICE to supply ice machine on demand. |
Pump P-103 — Product Water Distribution Pump (T-102 → Espresso Machine & Drinking Water)
| Parameter | Requirement |
|---|---|
| Procurement | Not yet purchased — select and record model here when procured |
| Manufacturer / Model | Grundfos CRN1S-8 or equivalent 3-phase variant (design baseline) |
| Pump Type | Vertical multistage centrifugal; close-coupled |
| Rated Power | ½ HP (0.37 kW) |
| Motor Type | 3-Phase induction motor; 208-230/460 VAC |
| Frequency | 60 Hz (MANDATORY — do not supply 50 Hz motor) |
| Speed | 3,450–3,500 RPM at 60 Hz |
| Full-Load Current | 3.2 A at 230 V 3-phase (typical for ½ HP class — confirm on nameplate) |
| Design Duty Point | 50 psi (115 ft head) @ 3 gpm |
| Wetted Materials | 316 stainless steel impellers, diffusers & shaft; EPDM O-rings |
| Shaft Seal | HQQE mechanical seal; food-grade elastomers |
| Connections | 1-¼″ Victaulic or NPT; mating fittings to be supplied |
| Speed Control | Controlled via VFD-103 (GS21-20P5); 0–100 % speed via Modbus RTU from PLC |
| Standards | NSF/ANSI 61; CE; cULus |
| Notes | Supplies pressurised treated water from T-102 to espresso machine (SanRemo Cafe Racer) and drinking water filling station. VFD maintains constant-pressure setpoint on distribution header (feedback from PT-104). P-102 is procured as CRN1S-4; P-103 may differ — document exact model when purchased. |
3.5 UV Disinfection Unit
| Item | Specification |
|---|---|
| Application | In-line; installed in the T-101 recirculation loop downstream of P-102 and upstream of the solenoid valve manifold (SV-RECIRC / SV-ICE / SV-TREAT). Runs continuously while P-102 is active — all water leaving T-101 passes through UV regardless of destination. |
| UV Dose | ≥ 40 mJ/cm² at rated flow; validated to NSF/ANSI 55 Class A or equal |
| Flow Capacity | Sized for continuous recirculation flow (min 2 gpm) |
| Chamber Material | 316L stainless steel or NSF 61 listed polysulfone |
| Power Supply | 120 VAC, 60 Hz, single-phase (supplied from control panel) |
| Control | On/Off via PLC relay output; UV hour meter recommended; runs continuously during system operation |
| Compliance | NSF/ANSI 55 Class A; UL listed |
3.6 Automated Ball Valve (Feed Water Inlet)
| Item | Specification |
|---|---|
| Type | Full-bore automated ball valve; electric actuator with spring-return (fail-closed) |
| Actuation | 24 VDC electric; 2-wire; spring-return to CLOSED position on power loss |
| Body Material | 316 stainless steel or food-grade brass |
| Seat / Seal | PTFE seat; EPDM or PTFE stem seals; food-grade |
| Control | On/Off via PLC relay output (P2-08TRS) |
| Compliance | NSF/ANSI 61 listed for potable water service |
3.7 Post-UV Solenoid Valve Manifold
Three solenoid valves are installed in a manifold immediately downstream of the UV unit. The PLC controls these valves to route UV-treated water from T-101 to the appropriate destination.
| Tag | Function | Normal State | Fail State | Notes |
|---|---|---|---|---|
| SV-RECIRC | Return UV-treated water to T-101 | Normally Open | Open (safe — water recirculates to tank) | Default path; closes when SV-ICE or SV-TREAT opens to direct full flow to demand path |
| SV-ICE | Supply UV-treated permeate to ice machine | Normally Closed | Closed (safe) | Opens on ice machine demand signal (FS-101); no mineral injection — ice machine receives pure RO permeate |
| SV-TREAT | Route water to mineral injection → T-102 | Normally Closed | Closed (safe) | Opens when T-102 level is below setpoint; water passes through metering pumps before entering T-102 |
Solenoid Valve Specifications (all three):
| Item | Specification |
|---|---|
| Type | 2-way, direct-acting or pilot-operated solenoid valve |
| Body Material | 316 stainless steel or food-grade brass |
| Seat / Seal | PTFE seat; EPDM or PTFE seals; food-grade |
| Size | ¾″ or 1″ NPT to match process piping |
| Actuation | 24 VDC coil; DIN connector |
| Response Time | < 500 ms open/close |
| Pressure Rating | ≥ 100 psi |
| Control | On/Off via PLC relay output (P2-08TRS #2) |
| Compliance | NSF/ANSI 61 listed for potable water service |
3.8 Mineral Injection Metering Pumps (× 3)
| Item | Specification |
|---|---|
| Quantity | 3 pumps (Mineral A, Mineral B, Mineral C) |
| Manufacturer / Model (procured) | Grundfos DDC 6-10 AR-PVC/V/C-F-31 — order code 001FG (× 3) |
| Type | Diaphragm metering pump (dosing) |
| Max pressure | 150 psi |
| Rated output | 6 L/h (1.5 US gph) |
| Power | 22 W |
| Wetted Materials | Per model: PVC head variant; PTFE diaphragm — verify NSF/ANSI 61 suitability for potable use |
| Turndown | Must support stable dosing below 5 mL/min (verify against DDC curve at operating pressure) |
| Pressure Rating | 150 psi maximum (per model); system operating point must be within pump capability |
| Power supply | 100–240 VAC, 50–60 Hz; controllable via PLC relay output (on/off dry-contact) |
| Adjustment | Digital control; onboard display per DDC series |
| Application | Inject minerals into water stream between SV-TREAT and T-102 inlet; dosing rate set by active HMI recipe preset |
| Alternates (reference only) | ProMinent Gamma X, Iwaki, LMI/Milton Roy PD series, Walchem — if spare needed |
Standard Mineral Concentrates:
| Pump | Mineral Concentrate | Role in Coffee Water Profile |
|---|---|---|
| Mineral A | Magnesium sulfate (MgSO₄) | Extraction enhancer; brightness and clarity |
| Mineral B | Calcium chloride (CaCl₂) | Body and mouthfeel; total hardness |
| Mineral C | Sodium bicarbonate (NaHCO₃) | Buffer capacity / alkalinity; balance and sweetness |
4. Instrumentation & Sensors
| Tag | Device | Range / Output | Location | Notes |
|---|---|---|---|---|
| PT-101 | Pressure Transmitter | 0–300 psi; 0.5–4.5 VDC | Feed water inlet | Dataq #2000361-300H or equal; 316SS wetted; ⅛″ NPT |
| PT-102 | Pressure Transmitter | 0–300 psi; 0.5–4.5 VDC | RO feed (high-pressure side) | Pre-membrane; monitors pump output pressure |
| PT-103 | Pressure Transmitter | 0–300 psi; 0.5–4.5 VDC | RO permeate outlet | Monitors membrane performance; low side |
| PT-104 | Pressure Transmitter | 0–300 psi; 0.5–4.5 VDC | P-103 discharge / distribution header | Feedback for constant-pressure VFD control |
| FT-101 | Flow Meter — Feed | Pulse output; 5–24 VDC | Feed line to RO | Used for recovery calculation; paddle or mag type |
| FT-102 | Flow Meter — Permeate | Pulse output; 5–24 VDC | Permeate to T-101 | Used for recovery calculation |
| FT-103 | Flow Meter — Distribution | Pulse output; 5–24 VDC | P-103 discharge to POUs | Monitors distribution flow to espresso machine / drinking water |
| CT-101 | Conductivity Sensor | 0–2,000 µS/cm; 4–20 mA | Feed water | Feed TDS measurement; inline flow cell |
| CT-102 | Conductivity Sensor | 0–200 µS/cm; 4–20 mA | Permeate outlet (before T-101) | Permeate TDS; used for salt rejection calculation |
| CT-103 | Conductivity Sensor | 0–200 µS/cm; 4–20 mA | T-102 inlet (after mineral injection) | Verifies final TDS matches active recipe setpoint |
| TT-101 | RTD Temperature Probe | Pt100 or Pt1000; 3/4-wire | Feed or permeate | Temperature compensation for conductivity & flow |
| LSH-101 | Level Switch — High | Dry contact (N.O.); 24 VDC | T-101 (RO Permeate Tank) | High level → stop RO feed pump (P-101) |
| LSL-101 | Level Switch — Low | Dry contact (N.O.); 24 VDC | T-101 (RO Permeate Tank) | Low level → stop recirculation/transfer pump (P-102); alarm |
| LT-102 | Continuous Level Transmitter | 4–20 mA (0–100 % level) | T-102 (Treated Water Tank) | Replaces discrete float switches on T-102 (5-gal tall/narrow tank); ultrasonic or capacitive; top-mount; PLC derives high, low, and fill setpoints from continuous signal; provides proportional fill level for smarter control and volume tracking |
| FS-101 | Flow / Demand Switch | Dry contact (N.O.); 24 VDC | Ice machine supply branch | Detects ice machine water demand; PLC opens SV-ICE when active |
All instrumentation in contact with product water shall be rated NSF/ANSI 61. Sensor connections to the PLC are via the Automation Direct P2-16ND3 (digital), P2-08AD-2 (analog 0–10 VDC), and P2-06RTD (RTD) I/O modules. The LT-102 continuous level transmitter (4–20 mA) connects to P2-08AD-2.
5. Control System
5.1 PLC — Automation Direct Productivity2000
| Item | Specification |
|---|---|
| CPU | AutomationDirect P2-550 Productivity2000 |
| Base / Rack | P2-08B — 8-slot base (6 slots populated; 2 open for future expansion) |
| Programming | Free Productivity Suite IDE (ladder, function block, structured text) |
| Communications | Dual Ethernet (RJ45); RS-485 Modbus RTU; RS-232; USB; microSD |
| VFD Interface | All three VFDs communicate via RS-485 Modbus RTU from PLC RS-485 port (daisy-chained) |
| HMI Interface | Ethernet (TCP/IP) to C-more HMI panel |
| Power | 12–24 VDC from panel-mounted DIN-rail power supply |
| Enclosure | NEMA 4 rated control panel; UL 508A listed enclosure recommended |
5.2 I/O Module Summary
| Module | Part Number | I/O Points Used | Spare Points |
|---|---|---|---|
| 16-pt 24 VDC Discrete Input | P2-16ND3 | 9 (2 level T-101, 3 flow pulse, 3 VFD status, 1 ice demand) | 7 |
| 8-pt Form-C Relay Output #1 | P2-08TRS | 8 (ball valve, UV, 3 metering pumps, 3 VFD run/stop) | 0 |
| 8-pt Form-C Relay Output #2 | P2-08TRS | 3 (SV-RECIRC, SV-ICE, SV-TREAT) | 5 |
| 8-ch Analog Input (0–10 VDC / 4–20 mA) | P2-08AD-2 | 8 (4 pressure, 3 conductivity, 1 level LT-102) | 0 |
| 6-ch RTD Input (Pt100/Pt1000) | P2-06RTD | 1 (feed/permeate temperature) | 5 |
5.3 Variable Frequency Drives
IMPORTANT: All three drives accept 200–240 VAC single-phase input (standard US 240 V service). No 3-phase utility supply is required. Motors must be 60 Hz rated.
| Parameter | VFD-101 (RO Feed Pump) | VFD-102 (Recirc/Transfer Pump) | VFD-103 (Distribution Pump) |
|---|---|---|---|
| AutomationDirect Part No. | GS21-21P0 | GS21-20P5 | GS21-20P5 |
| Rated HP | 1 HP (drives ¾ HP motor) | ½ HP (drives ½ HP motor) | ½ HP (drives ½ HP motor) |
| Input Voltage | 200–240 VAC, 1-phase | 200–240 VAC, 1-phase | 200–240 VAC, 1-phase |
| Input Frequency | 60 Hz | 60 Hz | 60 Hz |
| Rated Input Current | 10.8 A (CT) / 11.3 A (VT) | 7.3 A (CT) / 8.3 A (VT) | 7.3 A (CT) / 8.3 A (VT) |
| Output | 0–230 VAC, 3-phase, variable freq. | 0–230 VAC, 3-phase, variable freq. | 0–230 VAC, 3-phase, variable freq. |
| Control Interface | RS-485 Modbus RTU from P2-550 | RS-485 Modbus RTU from P2-550 | RS-485 Modbus RTU from P2-550 |
| Speed Control | 0–100 % via PLC setpoint (Modbus) | 0–100 % via PLC setpoint (Modbus) | 0–100 % via PLC setpoint (Modbus) |
| Protections | Motor overload, over/under voltage, over-temp, short circuit | Motor overload, over/under voltage, over-temp, short circuit | Motor overload, over/under voltage, over-temp, short circuit |
| Config Software | GSoft2 (Free — AutomationDirect) | GSoft2 (Free — AutomationDirect) | GSoft2 (Free — AutomationDirect) |
5.4 HMI Display
| Item | Specification |
|---|---|
| Model | AutomationDirect C-more EA9-T10WCL |
| Display | 10.1″ widescreen colour TFT LCD; 1024 × 600 WSVGA; LED backlight |
| Touch | Resistive single-touch; industrial-grade |
| Enclosure Rating | NEMA 4/4X (IP65); suitable for wet / washdown environments |
| Interface | Ethernet to P2-550 PLC; USB; RS-232/485; SD card slot |
| Power | 12–24 VDC |
| Programming | Free C-more EA9 Designer software |
| Key Displays | Feed pressure, RO feed pressure, permeate pressure, distribution pressure, feed flow, permeate flow, distribution flow, feed conductivity, permeate conductivity, treated water conductivity (actual vs. recipe target), temperature, RO Recovery %, Salt Rejection %, T-101 level status, T-102 level status, VFD-101/102/103 speed, solenoid valve states, active water recipe name and parameters, system alarms |
5.5 HMI Water Recipe Management
The HMI shall provide a dedicated recipe management screen allowing the operator to create, edit, select, and activate water mineral profiles for the espresso machine.
Recipe System Requirements:
| Item | Specification |
|---|---|
| Recipe Storage | Minimum 10 named presets stored in HMI non-volatile memory |
| Parameters per Recipe | Mineral A dosing rate (mL/gal), Mineral B dosing rate (mL/gal), Mineral C dosing rate (mL/gal), target TDS (ppm) |
| Active Recipe | One recipe active at a time; displayed on main HMI screen |
| Recipe Selection | Operator selects from named preset list on HMI touchscreen |
| Feedback | CT-103 actual TDS displayed alongside recipe target TDS; deviation alarm if actual exceeds ± tolerance band |
| Recipe Change Behaviour | On recipe change, PLC applies new dosing rates on the next T-102 fill cycle; HMI displays estimated fill cycles to fully transition T-102 to new recipe |
Example Factory-Loaded Presets:
| Preset Name | Mineral A (MgSO₄) | Mineral B (CaCl₂) | Mineral C (NaHCO₃) | Target TDS |
|---|---|---|---|---|
| SCA Gold Cup | 2.4 mL/gal | 3.1 mL/gal | 1.8 mL/gal | ~120 ppm |
| Light Roast — High Extraction | 3.6 mL/gal | 1.5 mL/gal | 2.0 mL/gal | ~100 ppm |
| Medium Roast — Balanced | 2.0 mL/gal | 2.5 mL/gal | 2.2 mL/gal | ~130 ppm |
| Rao/Perger Water | 3.0 mL/gal | 0.0 mL/gal | 1.5 mL/gal | ~85 ppm |
| Custom 1 | (user-defined) | (user-defined) | (user-defined) | (user-defined) |
Note: Dosing rates shown are illustrative and depend on mineral concentrate strength. Actual rates must be calibrated during commissioning using laboratory-verified TDS measurements. The system starts with RO permeate at near-zero TDS, so mineral addition is fully additive with no feed water variability.
5.6 PLC Control Logic Summary
The PLC shall implement the following control functions as a minimum:
Start/Stop & Sequencing:
- Automatic start/stop sequencing: pre-fill, production, recirculation, transfer, distribution, flush, and standby modes
- Automated ball valve control: open on system start; close on shutdown or fault
VFD Speed Control:
- VFD-101 (P-101): ramp-up on start; pressure setpoint PID control for RO feed pump
- VFD-102 (P-102): runs continuously; maintains recirculation flow setpoint; PLC may adjust speed when redirecting flow to ice machine or treatment path
- VFD-103 (P-103): constant-pressure PID control on distribution header (feedback from PT-104)
UV Recirculation Loop:
- UV lamp runs continuously while P-102 is active (effectively continuous during system operation)
- Default valve state: SV-RECIRC open, SV-ICE closed, SV-TREAT closed — water recirculates through UV and returns to T-101
- T-101 full volume circulates through UV approximately every 30–60 minutes at P-102 operating flow rate
Solenoid Valve Manifold Control:
- SV-RECIRC: default open; closes (partially or fully) when SV-ICE or SV-TREAT opens to direct flow to demand path
- SV-ICE: opens when FS-101 detects ice machine demand; closes when demand ceases; PLC inhibits if T-101 is at low level
- SV-TREAT: opens when T-102 level falls below fill setpoint and T-101 has adequate level; closes when T-102 reaches high level
Tank Level Management:
- T-101: start RO production (P-101) when level drops below low-set; stop P-101 on high level; if T-101 reaches critically low level, stop P-102 to protect pump
- T-102 (continuous level via LT-102): PLC reads 4–20 mA level signal and derives software setpoints — fill-start (e.g. 30 %), fill-stop / high (e.g. 90 %), low-alarm / stop P-103 (e.g. 10 %). Open SV-TREAT and enable metering pumps when level falls below fill-start; close SV-TREAT and stop metering pumps at fill-stop; stop P-103 on low-alarm. Continuous signal also enables HMI display of real-time T-102 fill percentage and estimated volume remaining.
- Cascade interlock: if T-101 is low AND T-102 is low, prioritise RO production (P-101); inhibit SV-TREAT until T-101 recovers above minimum threshold
Mineral Injection & Recipe Control:
- Active recipe selected via HMI determines metering pump dosing rates
- Metering pumps enabled only when SV-TREAT is open (water flowing to T-102)
- Dosing is ratio-based relative to transfer flow; PLC calculates pump speed/duty based on recipe mL/gal setpoint and measured flow
- CT-103 provides closed-loop TDS verification; alarm if actual TDS deviates from recipe target by more than configurable tolerance
Monitoring & Logging:
- Calculated display values: RO Recovery % and Salt Rejection % — updated every scan
- Alarm monitoring: high/low pressure, low flow, VFD fault, high conductivity, level faults on both tanks, UV lamp fault, TDS recipe deviation
- Data logging via SD card: key process variables at configurable interval
6. Electrical Requirements
⚠ All electrical components must be rated and labelled for 60 Hz operation. Many imported motors and drives are 50 Hz–labelled; confirm 60 Hz compatibility on the nameplate for every motor, drive, solenoid, and transformer before purchase.
| Circuit | Description | Voltage | Current | Breaker | Wire Size |
|---|---|---|---|---|---|
| CB-1 | VFD-101 — RO Feed Pump (GS21-21P0) | 240 VAC | 10.8 A | 20 A 2-pole | 10 AWG |
| CB-2 | VFD-102 — Recirc/Transfer Pump (GS21-20P5) | 240 VAC | 7.3 A | 15 A 2-pole | 14 AWG |
| CB-3 | VFD-103 — Distribution Pump (GS21-20P5) | 240 VAC | 7.3 A | 15 A 2-pole | 14 AWG |
| CB-4 | Control Panel — PLC, HMI, 24 VDC PS, UV, metering pumps, solenoid valves | 120 VAC | ≤ 10 A | 20 A 1-pole | 12 AWG |
Additional electrical requirements:
- A lockable disconnect switch shall be provided within sight of each motor (NEC 430.102)
- VFD output wiring to motors shall use shielded cable to minimise EMI interference with PLC analog inputs
- All control panel wiring shall be in accordance with NEC Article 430 and UL 508A
- 24 VDC DIN-rail power supply shall be provided in the control panel for PLC, HMI, sensors, solenoid valves, and ball valve actuation
- All panel components shall be CE marked and UL listed where required
7. Materials of Construction & Sanitary Requirements
This system is intended for the production of drinking water for human consumption. All materials in contact with product water must be non-toxic, non-leaching, and compliant with applicable food-contact and drinking water standards.
| Component | Required Material | Standard |
|---|---|---|
| Pump bodies, impellers, shafts | 316L stainless steel | NSF/ANSI 61; FDA CFR 21 |
| O-rings and seals (pump / valve / fittings) | EPDM or NSF-grade Buna-N (Nitrile) | NSF/ANSI 61; FDA CFR 21 §177 |
| Membrane housing | Fibreglass-wound or 316SS | NSF/ANSI 58 or 61 |
| Filter housings | 316SS or food-grade polypropylene | NSF/ANSI 42 or 61 |
| Storage tanks (T-101 and T-102) | NSF-listed HDPE or 304L / 316L SS | NSF/ANSI 61 |
| Process tubing / piping | 316SS, HDPE, or NSF-listed CPVC / polypropylene | NSF/ANSI 61 |
| Fittings and valves | 316SS or brass (NSF listed); lead-free per Safe Drinking Water Act | NSF/ANSI 61; NSF/ANSI 372 (lead-free) |
| UV chamber | 316L stainless steel or NSF 61-listed polymer | NSF/ANSI 55 Class A |
| Metering pump wetted parts | PTFE diaphragm, PVC/PP/PVDF head, FKM or EPDM seals | NSF/ANSI 61 or FDA CFR 21 |
| Ball valve body and seat | 316SS body; PTFE seat | NSF/ANSI 61 |
| Solenoid valve bodies and seals | 316SS or food-grade brass body; PTFE seat; EPDM seals | NSF/ANSI 61 |
Prohibited Materials:
- Lead-containing brass or solder in any water-contact fitting
- Galvanised steel — unacceptable for corrosion and contamination reasons
- Standard neoprene seals — use EPDM or PTFE only
8. Standards & Compliance
| Standard | Scope |
|---|---|
| NSF/ANSI 58 | Reverse osmosis drinking water treatment systems — system and component certification |
| NSF/ANSI 61 | Drinking water system components — materials in contact with drinking water |
| NSF/ANSI 55 Class A | UV microbiological water treatment systems — 40 mJ/cm² minimum dose |
| NSF/ANSI 42 | Drinking water treatment units — aesthetic effects (chlorine/taste/odour reduction) |
| NSF/ANSI 372 | Lead-free designation for all fixtures and fittings |
| FDA CFR 21 | Food contact materials — applicable for all elastomers and plastics in product water contact |
| NEC Article 430 | Motor and motor circuit requirements (USA electrical code) |
| NEC Article 440 | Air-conditioning and refrigerating equipment (applicable to hermetic motor compressors if any) |
| UL 508A | Industrial control panels — listed enclosure required |
| CE Marking | Required for all electrical components shipped to USA for resale |
8.1 Local Enforcement (San Diego County)
This system will be inspected by the County of San Diego, Department of Environmental Health and Quality, Food and Housing Division. Two permitting paths are viable:
- Stationary (recommended): the skid is treated as equipment in an existing permanent food facility (the host dessert shop). Regulatory anchor: California Retail Food Code (CalCode), Cal. Health & Safety Code §113700 et seq., enforced via SD DEH plan-check for equipment additions. The host facility's existing handwashing, warewashing, water heater, and wastewater infrastructure is leveraged; no separate sinks/tanks are added for the skid itself.
- Mobile (deferred unless the business case requires it): the skid would be plan-checked and permitted as a Mobile Food Facility under the SD DEH Construction and Operational Guide for Mobile Food Facilities and Mobile Support Units (DEH-FH-991, Rev 04/30/2021), which adds requirements for dedicated handwash + warewash sinks, water heater, wastewater tank at 150% of potable, commissary agreement, and an annual MFF permit.
Both paths converge on identical NSF/ANSI 61 requirements for water-contact equipment. The MFF guide is the more prescriptive of the two for water tanks specifically (§IV.H), so its provisions are cited below as the design-side controlling reference. Components and documentation that satisfy MFF §IV.H also satisfy CalCode for stationary equipment.
The relevant provisions for this system are:
| Citation | Requirement | Implication for this build |
|---|---|---|
| §III.E.10 | "All equipment shall be listed as certified or classified for sanitation by an ANSI accredited certification program, such as, NSF." | Every wetted component on the skid (tanks, pumps, filters, valves, fittings, tubing, UV chamber, instrumentation in product water) must carry NSF or other ANSI-accredited certification (NSF, ITS/ETL, UL EPH, CSA). Documentation must be available at plan check. |
| §IV.C | Equipment and plumbing must carry ANSI-accredited sanitation certification. "In the absence of applicable ANSI sanitation certification, the equipment design, construction and installation is subject to approval by this Department." | Provides an explicit plan-check approval path for components without formal certification (e.g. converted Sanke kegs for T-101 / T-102) — material declaration and design submittal are accepted in lieu of vendor-supplied certification. |
| §IV.H.1 | "Water tanks and plumbing shall be constructed of food grade material as approved by an ANSI accredited testing organization for drinking water." | T-101 and T-102 must use NSF/ANSI 61-listed material (or equivalent). NSF/ANSI 51 alone (food equipment surfaces, the typical default certification on stainless beer kegs) does not satisfy this — vendor confirmation of NSF 61 material compliance is required, OR plan-check approval per §IV.C must be obtained before installation. |
| §IV.H.2 | "Interiors shall be smooth and free of recesses and crevices and capable of draining completely." | Drives the electropolished interior preference and the dished/sloped bottom requirement on both T-101 and T-102. Tank outlet must be at the lowest point of the vessel. |
| §IV.H.3 | "Tanks must be adequately vented for flow. Water tank vents shall terminate in a downward direction and are to be covered with 16 mesh per square inch screen or equivalent..." | Both tank vents (T-101 and T-102) must use downward-facing sanitary vent caps with screened or filtered openings. |
All vendor documentation supporting these requirements (NSF certifications, material declarations, vessel approvals) shall be assembled into the plan-check submittal package alongside this specification.