Petrol Station, Fuel Depot & LPG Distribution ERP: Automated Wet-Stock Tank Reconciliation, Pump Meter Audits, and Corporate Fleet Cards

Why High-Volume Petrol Stations and LPG Distributors Lose Margin on Thin Spreads

Retail petroleum (PMS Super, AGO Diesel, IK Kerosene) and Liquefied Petroleum Gas (LPG) operate on razor-thin regulated per-liter margins coupled with massive daily cash and mobile-money turnover. If you operate a network of 3 to 50+ service stations, a bulk fuel depot, or an LPG cylinder refilling and distribution business, losing just 0.6% of your throughput to un-detected wet-stock shrinkage, pump attendant cash/M-Pesa manipulation, or un-returned empty LPG steel cylinders can wipe out half of a station's monthly net profit.

When station managers reconcile 6:00 AM and 6:00 PM shift handovers using paper dip-sheets and calculator tapes, three expensive blind spots occur: 1. Wet-Stock vs. Meter Variance—where underground tank dip/ATG readings decline by 10,400 liters while nozzle totalizer meters only account for 10,120 liters sold (hiding tank calibration drift, thermal contraction, delivery short-landing, or underground pipe leaks); 2. Attendant Shift Drop Float—where attendants reuse a single corporate M-Pesa Till payment message to justify two different cash drops; and 3. Corporate Credit Abuse—where paper LPOs (Local Purchase Orders) from B2B fleet customers are inflated to siphon extra fuel into private jerrycans. At devManue Energy & Downstream ERP Engineering, we build custom Petrol Station Wet-Stock, LPG Cylinder Tracking, and Corporate Fleet Fuel-Card Platforms.

1. Core Forecourt, Wet-Stock, LPG & Fleet-Card Modules & Build Costs

Our architecture connects your station forecourt, lube bay, convenience mart, and bulk depot into a single real-time headquarters control tower:

2. Deterministic Shift Nozzle Reconciliation and Wet-Stock Variance Auditing

At every shift change, the forecourt supervisor records the closing electronic/mechanical totalizer reading for every nozzle and the physical dip/ATG reading for every underground tank. Our engine computes the exact Book Closing Stock (Opening Dip Volume + Offloaded Tanker Delivery Volume − Net Metered Sales after Return-to-Tank calibration tests) and compares it against the Physical Closing Tank Dip Volume.

If the cumulative wet-stock loss on any tank exceeds the industry-standard evaporation tolerance (e.g., 0.25% for AGO Diesel or 0.35% for PMS Super), the system immediately triggers an executive SMS/WhatsApp alert to headquarters before the next fuel tanker is offloaded:

# Production Petrol Station Shift Nozzle & Underground Tank Wet-Stock Audit Engine
from decimal import Decimal, ROUND_HALF_UP
from django.db import transaction
from .models import UndergroundTank, ShiftNozzleReading, TankWetStockAuditLog

@transaction.atomic
def close_shift_and_audit_wet_stock(
    tank_id: int,
    shift_id: int,
    opening_dip_liters: Decimal,
    delivered_liters_at_20c: Decimal,
    closing_dip_liters: Decimal,
    nozzle_readings: list[dict],
) -> TankWetStockAuditLog:
    """
    Reconciles pump nozzle totalizers against underground tank physical dips,
    isolating attendant cash obligations from physical wet-stock tank variance.
    """
    q2 = lambda v: v.quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
    tank = UndergroundTank.objects.select_for_update().get(id=tank_id)

    total_metered_liters = Decimal("0.00")
    total_expected_revenue_kes = Decimal("0.00")

    for nr in nozzle_readings:
        gross_dispensed = Decimal(str(nr["closing_meter"])) - Decimal(str(nr["opening_meter"]))
        rtt_calibration = Decimal(str(nr.get("rtt_liters", "0.00")))
        net_sold_liters = max(Decimal("0.00"), gross_dispensed - rtt_calibration)
        pump_price = Decimal(str(nr["unit_price_kes"]))

        total_metered_liters += q2(net_sold_liters)
        total_expected_revenue_kes += q2(net_sold_liters * pump_price)

        ShiftNozzleReading.objects.create(
            shift_id=shift_id,
            tank=tank,
            nozzle_code=nr["nozzle_code"],
            opening_meter=nr["opening_meter"],
            closing_meter=nr["closing_meter"],
            rtt_liters=rtt_calibration,
            net_liters_sold=net_sold_liters,
            expected_revenue_kes=q2(net_sold_liters * pump_price),
        )

    # Book Stock = Opening Physical Dip + Tanker Offload - Net Metered Nozzle Sales
    book_closing_liters = opening_dip_liters + delivered_liters_at_20c - total_metered_liters
    wet_stock_variance_liters = closing_dip_liters - book_closing_liters

    throughput_base = max(total_metered_liters, Decimal("1.00"))
    variance_pct = q2((wet_stock_variance_liters / throughput_base) * Decimal("100.0"))
    max_loss_tolerance_pct = Decimal("-0.35") if tank.fuel_grade == "PMS" else Decimal("-0.25")
    is_breach = variance_pct < max_loss_tolerance_pct

    return TankWetStockAuditLog.objects.create(
        tank=tank,
        shift_id=shift_id,
        opening_dip_liters=opening_dip_liters,
        delivered_liters=delivered_liters_at_20c,
        metered_sales_liters=total_metered_liters,
        book_closing_liters=book_closing_liters,
        physical_closing_liters=closing_dip_liters,
        variance_liters=wet_stock_variance_liters,
        variance_pct=variance_pct,
        is_tolerance_breach=is_breach,
    )

3. Replacing Paper Fuel LPOs with Tamper-Proof Corporate Fleet Wallets

Corporate B2B fleet accounts (schools, logistics companies, factories, county vehicles) bring steady volume to your stations—but paper LPO booklets are rife with fraud. Our built-in Corporate Fleet Fueling Portal lets your B2B clients top up a prepaid wallet (or operate within an approved credit limit), register their vehicle plates and fuel-grade restrictions, and authorize fueling via a Driver One-Time QR/SMS Voucher or NFC Tag. The pump attendant enters the vehicle's current odometer reading and snaps a photo of the number plate, and the corporate client's fleet manager receives an instant WhatsApp/email receipt showing exact liters fueled and real-time kilometers-per-liter (km/L) efficiency!

Managing high-frequency telemetry and multi-branch POS streams? Size your ingestion workers with our Bulk Ingestion & Queue Planner or book a 30-Minute Energy & Forecourt ERP Discovery Call.

4. Frequently Asked Questions (FAQ)